It also adds download possibilities which is a nice add-on. A second possibility lets you view random deleted videos right at delutube.
So, if you ever come upon the dreaded “This video is no longer available” grab the id from the youtube page and try loading it with delutube. This does not work all the time, if it does not - delutube displays a message in the download box saying so. Videos get probably deleted physically as well after a period of time.