http://www.convertfiles.com/
I found this website when a client needed a DWG converted to a PDF. It converts just about anything but also contains a download method for Youtube videos.

http://file2hd.com/
This site is good for non-youtube videos. Keepvid.com is supposed to work on non-youtube but 9 times out of 10 it failed. File2HD extracts every media file from the site and creates a download link for it. You can then filter it for videos or audio. I use this site frequently for law firms that want to grab some obscure video or a news site's embedded video to use during legal proceedings.