I would not suggest moving the climbing aid/lanyard until you're on the tree stand platform because you will not have 3 points of contact as illustrated @ 15:55 of the video. Not with out the lineman's belt attached anyway. It Looks like he was off balance while moving it.
I would need to have completed post-doc work in multiple fields to figure out how to get the harness that came with my Viper to work. It doesn't resemble the harness in this video, but if more than a 2 minute clip is needed to demonstrate proper usage no one will use it.