This is how I see it;
Climber falling video
1. The branch he took was too big and heavy.
2. He was natural crotching, using blocks and lowering devices correctly allows for a more predictable outcome, natural crotching is subject to more unknowns(friction force over limb, tension on wraps, rope digging into crotch.
3. He left far too big a belly in the rope, which allowed the branch to drop too far and it built up more force as it fell further this combined with the force of friction over the crotch allowed for rope failure.
4. Because of the angle and weight of that stem he should have put a block in the main stem with the rigging rope going through that block 1st then into a redirect block on the branch he was taking out, this would have meant the main stem took most of the load of the branch and helped to dissipate the load throughout the whole tree. He could have then continued to lower the whole stem in sections through his redirect block, with the block in the main stem taking most of the load.
5. He only has 1 tie in point on the main stem, he should have been tied below the branch he was cutting.
6. Looks like it was the tail end of his line that saved him from a bad pendulum into the main stem.
7. He makes the top cut one handed, possibly because he is expecting a big ride so he holds on to a stub on with his left hand. He was lucky the movement of the tree didn't make him cut his left hand with the saw.
8. He is not wearing a helmet with a chinstrap, looks like he is wearing a baseball cap which flies off much the same way a groundie hardhat with no chinstrap would.
9. His saw gets ripped off at high velocity and is seen moving at high speed out of the tree. Probably the best outcome.
10. Lastly, it seems he carries on with the takedown, a big mistake given what has just happened, he should have finished it the next day after he had been for a medical checkup. It also would have given him the opportunity to inspect his harness rope and biners etc for damage( especially after his saw was ripped from his harness)
Climber falling video