A new system, which began rolling out to a limited number of uploaders on Tuesday, favours relevancy over recency and introduces better moderation tools. The new commenting system, which is powered by Google+ will show YouTube viewers the most relevant comments first, such as those by the video uploader or channel owner.
If a person is flagged for spam or abuse, don't be surprised to find your comments buried, and celebrities who have strong Google+ reputations will be boosted above others. Comments made on posts with YouTube links in the Google social network will show up on YouTube itself. So, you'll see comments from people in your Google+ Circles higher up, too.