Wikivid is mediawiki-based video-sharing thingy. A lot of good instructional videos about software (Flash, Illustrator, RoR, Logic, Maya, etc.), but the editing interface is clumsy. The just-the-facts approach makes seem like the creators wanted to make something "like wikipedia, but with video!" but that won't happen until you can actually edit the videos collaboratively online (I give it 5 years).