You can also use GreaseMonkey to download videos. Someone has written a user script so a little red bar appears on the top of the page that says "Save video as.." Instructions for this process can be found
here. They also have a link on the site to
here, which is a different way to do the same thing.
There are also links to FLV players and converters on the first site, though I would go with VLC, like Art said before.