I figure you have a ~45° area of fall if things get crazy. That may or may not matter, and should be accounted for. Not for every tree either.
edit:
I didn't study the video, but it looked like a notch was cut to allow for the jack. I wonder how much time is really saved if you're cutting a notch anyway.
edit:
I didn't study the video, but it looked like a notch was cut to allow for the jack. I wonder how much time is really saved if you're cutting a notch anyway.