I've got one. I haven't looked at it in awhile, but remember it being a little more sturdy than the one in the video. My take is that it's a heck of a lot better than lifting somebody up in the bucket, especially with a chainsaw. You can make the chain to the frame as short or as long as you need it and if the tie points are too flimsy you can go around something else. Keeping it tied and chained tight to the frame so that it can't wobble makes if feel much safer. When the cage is assembled and pinned together (vs hyper-extended and bent backwards) it seems safe enough. Sure, an angry operator could chuck you out.
If I had it to do over I would probably start with an IBC tote and modify, but it does what I need, which is mainly pruning trees in the fall. Unfortunately my trusted operator moved away to school this fall so I'm going to have to talk her into coming home for a weekend and driving me around.