I think it is a good way because if you have a sticker on the back of your jersey it will remind kids not to check from behind and cause other people to get injured very badly. If I were a professional hockey player I would wear the sticker because I don't want get checked from behind and get injured very badly and miss lots of games. Also if I were the head of the sticker thing, I would make sure all the players wear them and if any of the professional hockey players didn't wear one, I would ask the hockey board to suspend the players. But players will get used to the 'stop' stickers and just keep on checking. In our minor hockey leagues, we have to wear them or we can't play in the games.
Grapes is really cool.
I like all his rock 'em sock 'em videos. Those are cool. I don't think it would be a good idea because it would be a waste of money. Most of the people in my league don't care they do it any way. If you are not expecting something like that to happen you shouldn't be playing.