Hello. Youtube guidelines have age restrictions, but if you, as a guard or parent give permission for it, it will be fine to upload and make videos. Not many parents are really into the game, cause of media. I will just give one tip for your son:
He (excuse me if I wrote gender incorrectly) just need to make videos. But he need to try to make each video a little better than the previous one. This will lead him to an awareness of his own work and responsibility for it. You can forget about editing, since its just too difficult for a 7-year-old child, most likely the best option would be shooting in one take. If he wants to talk in his videos, he has to train this skill. Im only 16, but I started reading aloud when it was tedious to do voice acting for a video.