I think it's great. I love the inventiveness of these guys. It's about having fun. Sure it's a wee bit more dangerous than a conventional chain saw, but they are really dangerous tools in the wrong hands, even with all the safety devices, so the guy knows what he is working with. I don't think he is stupid. I doubt if we will see them in the screwfix catalogue any time soon.
As for the chain oil feed!!! that is pure dead brilliant!!! a good lateral thinker!!
What kind of welder is he using?