This is one of the hottest applications I have downloaded in a while - Miro. Think of iTunes / RSS reader for Internet TV. It offers a wonderful channel guide, allows subscribing to feeds, plays most any video formats, does bit-torrent if the internet-video-site offers it, and most importantly, manages the lifetime of your downloaded videos. By default, watched videos expire after five days after which they get deleted automatically. You can tell Miro to automatically download new/all videos in a channel or just tell you if there is anything new.