Podcache.

What is podcache? (not related to the podcast RSS standard)

It is an open source FireFox plugin (1.5 only for now).
It downloads videos in your queue and caches them locally, and then rewrites wepages if it finds links to cached videos in them. It is clever about not downloading too much stuff, and deleting stuff you've watched.
It makes watching videos online more enjoyable.
So it helps videobloggers.
Screenshot.