only pain will you find

All these responses are great--but perhaps Yoda had already seen the security recordings. He probably wanted to be sure, too. Yoda's the main man, he'd be checking that recording out! Just a thought. I think he sensed it too, as did Obi-Wan.

Yoda knew, he could sense it. I dont' think he suspected Anakin of foul play before. All the Jedi were suspicious of Anakin's powers esspecially since he was all buddy buddy w/Palps,though. But nobody would have dreamed Anakin would go as far as he did.
Obi-Wan would have believed Yoda even without the proof because Jedi don't lie to eachother about that kind of stuff. And don't say Obi-Wan lied to Luke about Anakin because that is completly different since Obi-Wan didn't actually lie. It was the truth from a certain point of view.

darth_frared put forth the following:

a) did yoda know? and how did he? i know this might come off as silly, but did he actually suspect something from anakin all along?

I honestly believe that Yoda knew. From Kashyyk onwards he suspected that Anakin had turned and by the time he and Obi-Wan get to the temple and confront the extent of the massacre, Yoda's already dropping hints to Obi-Wan as to who the perpetrator is (this padawan killed by lightsabre he was), but Obi-Wan is either too slow on the uptake or he's just in big denial as I believe JediMomma already stated.

I think it was dawning on Obi-Wan anyway. It's the only way I can reconcile myself to the fact that no one asks about Anakin's welfare when they learn of the clone trooper rebellion and the temple raid. Obi-Wan doesn't ask Yoda if he knows anything of the whereabouts of his former Padawan, and Yoda doesn't venture any insight into it either. For such a major character as Anakin, who rightly or wrongly is considered the chosen one, I found it odd that they did not bring him up at all as they were discussing what to do next. For me, this lends itself to the idea that they were all thinking it but no one really wanted to say it, well at that point, not Yoda, not till he got to the temple anyway.

b) had obi-wan not asked, when would he have wanted to tell obi-wan? and how would obi-wan have believed him? i mean, yoda just saying, alright, you know, it was anakin, would not have made much sense without the recording, would it?

See above for some of that. I think Yoda got the ball rolling with his comment on how the padawan had lightsabre wounds on his body, and that was going to start sinking into Obi-Wan's mind and get the wheels turning, as it were. The recording is the visual that Obi-Wan had to see no matter what, even if he already knew in his heart that it was so, sometimes you just have to be hit with a visual when it's that serious. Yoda's warning is really just, at that moment, compassion on his part for Obi-Wan, knowing that Obi-Wan would be devastated by this confirmation. I really think they both are on the same page already, they both think it was Anakin's doing, but Obi-Wan was closer to Anakin than Yoda was and I guess just once, Yoda showed he was a feeling Jedi (can't say human, since he's a little green biped)and acknowledged how hurt Obi-Wan would be by this.

i thought it was odd, too. they agree that they need to warn the straddlers and don't think about who did it.

and if yoda was so sure (i don't really buy the idea that he checked before obi-wan, i think he simply sensed it) why wait so long and/or keep obi-wan half-heartedly from watching? they might have suspected the sith did it (who else, really?) but i find it odd they don't talk about it.

exactly.

i'm not sure what NB means...
he didn't say no, of course, he says, only pain you will find, and he was right. the question was, if obi-wan hadn't volunteered to look at the recordings, would he have believed yoda saying, it was anakin? and with padme i think we have a possible reaction to this statement. she might be in denial, too, no doubt, but she finds it hard to believe, as obi-wan IMHO would have done.

but that's hindsight, sinister. it could be sid has found some run-of-the-mill apprentice somewhere who did it, that wouldn't be nearly as painful as finding out anakin has done it.
they don't know yet, that sid doesn't like fighting. or obi-wan could suspect some other apprentice to have done it. they never knew who was next, did they?

i wasn't talking about lying. i'm more sort of talking, how much do you believe that your best friend has done that? padme shows us that even though she *knew* he had killed before (not in cold blood, though) she was still convinced it could not have been him.
and you'd think obi-wan would just go, *shrug* okay, it was anakin then? nah, the guy is not dumb.

yeah, i agree.
but do you think obi-wan could have been convinced by simply being told?

hm, yes, i think we all agree on that. but but but ... had obi-wan not asked, i don't think yoda would have encouraged him, so how was he going to break the news to him, if obi-wan was in denial and yoda kind of too?

all those tricky questions.

NB= nota bene, latin for note well or take note of.

I believe Yoda's plan was - wait for Obi to come the realization himself - he was trying to "lead him" there - "...this padawan... killed by lightsaber." If that didn't work in a reasonable time, I'm sure he intended to tell him. If Obi remained in denial - then there was the video tape. Seems pretty simple to me.

And as for why "..no one asks about Anakin's welfare when they learn of the clone trooper rebellion and the temple raid..."
OBI-WAN: How many other Jedi managed to survive?
YODA: Heard from no one, have we.
What was Obi going to say? Not even Anakin? Yoda would have said, "You understand not what part of no one?"
And then there was...
OBI-WAN: Have we had any contact from the Temple?
YODA: Received a coded retreat message, we have.
What was Obi going to say, "Just that, nothing from Anakin?" I think he would have earned a gimmer stick whack from Yoda w/ that one.

about Obi-Wan earning a gimmer stick with that last question. I agree. Given the magnitude of what was happening, I'm glad Yoda and Obi-Wan weren't obsessed with Anakin like Anakin was with himself.

Think back (or forwards?) to Obi and Luke at the Sandcrawler in ANH.
It is the same thing we are seeing here.

Obi is leading Luke to a realisation, towards something he has to confront - his destiny, which is to leave Tatooine and become a Jedi.
But he is trying to do it gently, he's making Luke think about these questions himself, rather than have Luke come face to face with his dead Uncle and Aunt; or just blurting out "The troopers did this, and your foster parents are dead".
"They didn't, but we were meant to think they did... These tracks are side by, Sandpeople always ride single-file to hide their numbers... And these blast points..."

I see Yoda as doing the same, he knows the truth and he is leading Obi gently into it from the moment they arrive at the Temple.
"Killed not by clones, this Padawan. By a lightsaber, he was."
Obi is destined to have to fight his former apprentice - which is a painful thing to have to do.
Just as Luke works out the truth about the droids and what must have happened to his foster parents already, he still rushes to see it with his own eyes.
Which really is pain he could have avoided - he knew what he needed to know.
The same goes for Obi-Wan, deep down he knows the truth, but he wants to see it with his own eyes.
He already knows who is responsible before he watches the footage - but he does not want to believe.
Watching the footage is unecessary pain.

Absolutely - beautiful parallel!

And again - this was why Yoda didn't initally answer Luke's question, "Is Darth Vader my father?" Luke KNEW. Yoda wanted him to see it himself - w/o external confirmation.

OBI-WAN: "Who could have done this?"

I thought it was kind of odd. I mean, they know there is a sith on the loose, so you would think their first suspicion would be that the sith master finally made a move.

Beat me to it. this was my first thought too. I mean they are fighting the Sith .ObiWan has fought Sith . Jedi and Sith use Lightsabers. i thought it odd that Yoda would assume it was Anakin before they entertain the Idea that a Sith may have killed them .