Re: my sensei "video clip"
The throw definitely looks like what I have seen Shioda do on tape. It definitely puts the neck and upper back at risk-more the neck. Also the possibility of a head injury is of great concern since the person is being driven straight down-head stops, brain continues to move - voila concussion. If the back of the brain hits the skull then we have issues of coordination as the cerebellum is being injured.
So, from what I saw the risk of a bad whiplash or strain injury or a broken neck or a concussion are all possible if the uke is not able to take the fall. Dangerous at best. IMHO.
As to Adam's comments, let me just say there are very effective iriminages taking the uke's balance out without driving the head and neck straight into the ground. If you want to realistically finish them off so they don't get up from it, then that is a good move. Does it take a broken neck or a severe concussion with permanent repercussions to drive the dangerous aspect of this home?