When you sign up to YouFolders with your Google mail associated with your YouTube account, YouFolder retreives your subscription list from YouTube and the magic starts.
After syncronizing with YouTube, you can create new custom folders by grouping your subscriptions into different topics. You can manage these custom feeds by bookmarking, junking or filtering them. Also, you can eliminate watched videos if you prefer.
You can also use inline video tools in video player and perform your operations instantly. Some of these tools are YouTube thumbnail grabber, tag extractor and subtitle downloader.