YouTube will soon be modifying the way comments are handled, using Google+. Currently, comments are ordered by the most recent, but with Google+ integration, comments will be based on relevance.
Starting this week, YouTube comments powered by Google+ will appear on your channel discussion tab. Top comments will be reserved for the video’s creator, popular personalities, engaged discussions about the video, and people in your Google+ Circles.
You will also have the option of posting publicly or privately. Comments can be viewed by everyone on Google+ and YouTube or limited to only the people in your Circles.
New moderation tools will be added to review comments before they’re posted, block certain words or auto-approve comments.
Source: YouTube Blog
