About this trick
I saw this trick done by Seth Peterson (who, as far as I know, is the creator of the trick) on  an insane video by Citadel, Things That Repeat.  It's a very eye-pleasing trick, somehow almost looking impossible to do.

The trick does tend to snag quite a bit, simply due to the fact that you're doing the whole trick from a backspin mount (aka a mount you would normally bind from), but with some practice and tweaking of your movements, you can consistently do it.