Good videos that is. High quality entertainment by preference. Not idiots pratfalling themselves to the tune of canned laughter.

Also, please don't link to videos only vissible in your own nation. It kinda sucks for everyone else.
For example...
Red VS Blue: http://redvsblue.com/archive/?sid=rvb&season=1
Has just finished it's 7th season. Plus inumerable shorts and 'public service announcements'. Early seasons are rather anarchic, and have poor resolution. The named seasons (Recconstruction & Reccreation) are very plot-driven, but may not make sense without seeing some of the earlier episodes.
One of my favorites remains their introduction to the internet. I may have mentioned this before:
http://www.youtube.com/watch?v=eRnoUNwFOkE
Mr Deity
On the problems of world building: http://www.youtube.com/watch?v=2Clm6nlWxzc
The the fine art of negotiation: http://www.youtube.com/watch?v=Z6IH2daZDnw
On theimportance of family: http://www.youtube.com/watch?v=mII6-IyaT3o