Ha. I ended up running across these same videos just a few days ago. The algorithm wants us to watch Kariya apparently.
He's a really thoughtful and intelligent guy. It's definitely troubling that he has no recollection of the hit, the rest of the game, and I believe he said even the next game.
I remember some years ago Troy Aikman talking about taking a hit to the head, being in the locker room, having conversation with the trainer, and I believe going back in the game, and having no recollection of any of it.
The league still needs to do much better protecting players heads. Starting with severely punishing non-hockey plays that involve the head, like crosschecks and elbows.