First, there's quick integrated video sharing on Twitter through a bookmarklet. Find a video on any website and you can send it to your Twitter buddies with a click. Neat.
ffwd goes a step further, trying to turn your Twitter account into a Twitter television of sorts; a feature called Twitter Connect lets you populate your Twitter stream with ffwd channels and videos. You might want to create a new Twitter account if you plan to do that, because not all users will be happy to be swarmed with videos in their Twitter streams.
Furthermore, you can add your Twitter account to your ffwd profile, which will create a "virtual TV channel" with all the videos you've ever shared, saved or tweeted. Other users can also sign up and follow your channel as they follow your Twitter account.