Hard Core Unicycling.

I thought so too! I didn't want to say anything though because I really don't understand where those things go on a bike. I think there must be a space-time warp pocket thing that y'all learn to tuck them into.

(Actually, I suspect that one leg is high enough to stand up just enough, but I'm not quite sure and willing to let it be a mystery like a Ricky Jay trick.)

Part of the trick looks to be him grabbing the seat with one of his hands, which hopefully minimizes the impact for his little dudes. If you watch the video, you can see him doing that whenever he makes a big jump.

Yeah, I think he grabs the seat and holds it outside the danger zone with his hand. There's a few on the other video that I have no idea about, but at this point I think I'll start working and stop thinking about little guy logistics.

Isn't Ricky Jay the guy on Deadwood?

From what I've gathered watching the youtube vids, I think he had a small part on that show.