I think I know which video he is talking about. I watched it, and I wanted to build a Pro-Line Slash also. The car they built in the video looked great when it was all finished.
I built a drag Slash from the ground up. I wouldn't just go buying all the stuff from that video and trying to copy it. The Pro-Line transmission is pretty cool, but overpriced at the time I built mine. I went with the aluminum Hot Racing trans housing and their steel 32p spur set. Nice stuff...