PicLens is an awesome browser extension that turns photos or images from popular sites in to immersive slide shows has added support for Youtube videos. I covered Piclens in last june, and this is one of the popular article in this blog.
PicLens supports Flickr, Photobucket, Picasa Web Albums, Fotki, FotoTime, deviantART, Smugmug, Facebook, MySpace, [...]