Youtube isn't just for music anymore, there's just about any instructional video you could want there. Just this morning I found one on how to get all my music from my iPod to iTunes on a different computer. You'd think downloading iTunes again would be enough for all my music to transfer over... but noooooo. Anyways, it made me think about how often I used youtube for such purpose. I've used it to replace a graphics card on my computer, to change a thermostat on my car and different ones to assist me in making an Ursula costume. What have you used it for?
I learned how to cut a mango using Youtube. It was quite enjoyable, and I have done it very often in the time since.
i've learned how to oil paint, build a tattoo machine, wirewrap jewelry techniques, recognize narcissistic traits in people, detox my pineal gland, how to beat levels on video games, cut the bottoms off of glass bottles, and the "right way" to eat an apple.
One of my former professors back at UC Davis put up a whole lecture series for the first part of Quantum Field Theory. It's pretty good, you get a really quick review of quantum mechanics and relativity and then he goes straight into the subject.