RE “tremendous tension” on top. Yes it will be a lot more than usual but easy to deal with. You just make your face cut shallow then do your back cut. If you are worried about barber chair then use a plunge cut for the back cut. Remember too that it looks like it is hung in the other tree so that reduces the tension.Ther is also a good alternative shown in the first referenced video to bore a square hole in the trunk and use a smaller limb in the hole to roll the tree.
Part of the hazard with this situation is in separating the stump from the trunk due to the tremendous tension in the trunk while it is still attached. Once the trunk is separated the problem gets MUCH easier.
This is basically what our instructor taught. Cut a little on the top compression and then walk the bar around an come up from the bottom.
Yes.