Plays all the YouTube links it can find in a web page, one after another.
PlayAll will find as many links to YouTube videos as it can on a page, then play them one after another in a box on the page. Now you don't have to open a new tab for each video, and you don't have to hunt the next link down every time a video ends. You can just sit back and let them all play.
It's open source, so if you want to look around or change something, go for it: