I can understand that they want to "update and improve the site", but this seems a bit like a step backwards. They know that Google+ isn't that popular, because it's overshadowed by Twitter and Facebook in the social networking market. Since YouTube is a popular site that Google just so happens to own, they're using that as a way to get more people on Google+. "If you want to keep commenting and uploading videos to YouTube, help us bolster the number of Google+ users by starting an account. We don't care if it takes away some useful features or makes the site more convoluted than it should be, just boost our numbers so we can call Google+ 'successful'."
I really hate that they messed with the comments section. Now the comments aren't listed in chronological order, but by how popular they are, or whatever comments use the stupid "+" tags.
Even Jawed Karim (one of YouTube's founders, and poster of the very first video) didn't like it. On his channel, he's got a comment on there that says "why the [censored] do i (sic) need a google+ account to comment on a video?"
Like I said, I can understand wanting to "update and improve a site", but this is purely being used to bolster the number of users on a social networking site that few people want to be a part of by just shoving it in their faces. I would much prefer it if it was optional. The people that want to connect to it can do so, and the people who don't want to can just say they don't and not be bothered with it again.
Google+ Video.... erm... YouTube is certainly becoming a pain in the neck.