There's already a perfect solution to getting notifications when new video's are posted on a channel, RSS. It won't bug me unless I ask it to, I don't need a YouTube account for it and I don't have to guess what the (3) next to the channel name actually means (new upload? new like? new algorithm glitch?). I might like to do the same for "Community" posts for some channels but it doesn't look like they do RSS for that (yet?).