I always thought it would be good to share your videos with the dev since this where a lot of devs come to start and find their growth, so instead of fighting with the youtube search they could get traction on their game page along with being able to see peoples feedback and reaction to their game. I may be wrong though, but I think if the developers had a problem with people commenting on their page they'd remove it or ask people not to do it. But I feel its a win-win for both parties involved, devs get page traction and smaller youtubers have a bit of exposure since it can be really hard to get noticed on youtube.