As was promised by YouTube boss Steve Chen back in November, the site is now giving viewers the option of watching some videos in higher quality.
The streams are available on certain videos, based upon the source file uploaded, and more are promised over time.
This better quality streaming applies to all eligible videos uploaded from the YouTube community, and is not restricted to partner content.
On the YouTube Account page users can now select the options "always show me higher quality when available" or "never show me higher quality".
But YouTube suggests that only folk with a fast internet connection opt for the higher rates.
The YouTube blog states: "Our philosophy is to make sure that as many people as possible can access YouTube and that videos start quickly and play smoothly".
"That's one reason why you don't see us racing to call this 'Super Duper YouTube HD' because most people don't want to wait a long time for videos to play."