Automatically doubles YouTube resolution to 720p for pixel-perfect Retina Display support.Retina YouTube is a Safari Extension that automatically doubles the resolution of YouTube videos to 720p (or 1080p if desired).
Only works in the YouTube HTML5 player, join at (http://youtube.com/html5).
Flash is currently unsupported, because Flash embeds are scaled natively by Safari to 2x, making 1:1 720p video on a Retina display impossible in a flash container.