Super vid,
you can really see how much force was working in that stem despite the side rope wood fibres still pulled out in the hingewood on the left looking from the back cut. (In trees with less lean and with good sound timber you can use differences in hinge thickness to pull the tree around slightly in the fell, takes quite a lot of practice and experience to be confident that you have enough control, and you'd always back it up with a static control line)
Falling trees with leans really takes careful planning and working through the variables, having a simple check list or felling plan to go through each time helps to make sure we don't neglect anything in the rush to get the job done.
There's a great flash animation showing the use of side rope control but no where near as instructive as your vid. (I will track it down though cause they use an friction hitch to keep tension in the side rope throughout the fall)
SF