Woah, that was lucky. I am always expecting root flairs to do that when I deal with blow downs like that. I also make my cut far enough away so I don't fall into the hole when that happens. He could have used that clam truck to hold the root stock in place while he made his cut and then safely let if flip back up when he was clear, I have done the same with an excavator once, worked out great. Bad luck when your saw gets grabbed like that but it happens. This guy really doesnt seem like he knows what hes doing. Good example of why I always wear my helmet too.