The mashup is not a new art form. I've been a DJ Riko fan for a long time. But this is taking that to a whole new level. We're talking major composition, here, using Youtube as an instrument. Watch this right now:
In a completely unrelated note, are you familiar with the excellent service called ZamZar? It takes any media source on the internet--video or audio--and transcodes it to any format you want. I'm not saying I *HAVE* done this, since it's legally murky, but one could, if they were so inclined, take all of Katiman's "Thru-You" clips (since "Mother of all Funk Chords" is only the first of seven), run them through Zamzar, get them as MP3s, and drop them into your music player of choice.
I'm just sayin'.