I don't fully understand...why not just post your video to Youtube and then tweet the URL?
Another advantage: if you’re using twitter, it’s easier to get started with twitpic than with flickr, since you don’t need a new account. Obviously this does not apply if you were using flickr already.
And a ton of people use Twitpic:
There must be some advantage to the marketing of these kinds of "add on services" to simple things like twitter that draw people to them; either that or twitter is so stupid simplistic (and they keep removing features) that the market is drawn to add features that the core developers have no interest in maintaining.
That's really important.