It's aaalllll about the Martyn Ashton clip in Tricks and Stunts:
http://www.trials-forum.co.uk/topic/172990-quick-pedal-up-question/#entry2394936
Also, in your vid you do that odd throw the bike in front of you, come to a standstill then go for the up thing which kills your momentum and I can only imagine making things harder. Try riding in smooth, and riding straight into the move rather than jerking your weight on run-up.