Searching for YouTube videos is fun, but the videos are usually of such a low, compressed quality that sometimes it's hard to actually see what is going on. But YouTube is trying to fix that problem. It already supplies one option: You can set your YouTube account settings to play HD video when available, or you can attach "&fmt=18" to the end of the URL to display videos in a higher 480x260 quality. But now YouTube is supporting an even higher quality 1280x720 video format (identified by "&fmt=22" at the end of a link). The results are a pretty dramatic difference.
The downside is that very few videos support the higher resolution. Most people who upload YouTube videos do so with the video already compressed. If the video wasn't uploaded in a higher resolution video format, then using the new suffix doesn't change anything, and that lower quality remains a vast majority of the YouTube library. Unless YouTube actually starts making an effort to attract HD content, or better advertise the HD content it already has, I'm not sure that this will make much of an impact.