There's plenty of good Tenchi vids.
"Waiting for You" by Dan Gallacher
"The Pain of Ryoko's Heart" by Fly High Studios
"Chick Magnet" by More Than Toast
"So Wrong" (I don't remember who did this one. I don't have it anymore)
"One Shot Juanita" (Don't remember the author again... it's Pretty Sammy, but that still counts as Tenchi in my book.)
The Tenchi section of the DDR Project done to "Vol. 4" by Raver's Choice is cool.
There's lots of them out there. heh.
I'm making a Tenchi vid one of these days to "Yamerarenai, Yamerarenai" (Shin Tenchi Muyo theme song.) but who knows when I'll get around to it.
As for Gundam Wing.. no.. There's no such thing as a good Gundam vid. They all suck.