Careful downloading that, it is supposed to be a site loaded with malware.
Me too. I used to use Keepvid and then Hooktube, and both stopped working.
Supposedly it is possible to find and download the .flv file manually and then you just have to convert it.
Maybe need to look at a paid option. Egad.
Good discussion of YouTube download programs here
https://m.slashdot.org/story/338739