I've been on the receiving end of some of this type of behavior myself (Yoshinkan, nidan). It's not just "good hard training". It's more like "good hard game-playing".
The part where he plows the guy's head into the mat, then pats him as though he's a child to urge him up is the part where I think you can see the situation most clearly (about 0:40). Mori pretty clearly accelerates uke's head to the mat. It's purposeful. It's unnecessary.
If uke has practiced a million times to receive this "technique", what are the chances that we happen to see the one time he messes up? It's a lot more likely that uke can't really take this "technique".
Mori was a likable guy back in the early 90's, having interacted briefly with him a couple of times. The videos rather glorify him