Some more or less educational but surely entertaining YouTube links

So, I was bored and looking around on YouTube, and I guess I should share some of the nifty things.
Some of the links are listed in multiple categories.

Math:
http://www.youtube.com/user/chychochycho
http://www.youtube.com/user/Vihart

Physics:
http://www.youtube.com/user/minutephysics
http://www.youtube.com/watch?v=xdZMXWmlp9g + the series starting at http://www.youtube.com/watch?v=LPDP_8X5Hug which is the rest of the lectures.

Biology:
http://www.youtube.com/user/crashcourse

History:
http://www.youtube.com/user/crashcourse

Random stuff:
http://www.youtube.com/user/scishow
http://www.youtube.com/user/CGPGrey
http://www.youtube.com/user/1veritasium
http://www.youtube.com/user/destinws2
http://www.youtube.com/user/truthorfail