How does YouTube 3D flash player instantly switch to anaglyph in 1080p?

A 3D Youtube movie like this: http://www.youtube.com/watch?v=SmV4ieSpk4k can be watched in various 3D technics. I want to make a simular player but I can't understand how YouTube's 3D player can switch instantly from Side-By-Side to anaglyph and back to normal. And still running smooth!?!

This is what i tried: two video instances from a Side-By-Side video(1280x720) both are 200% width first one x/y = 0/0, second one x/y, -720/0

than with the OPTMI开发者_如何学编程ZED ANAGLYPH FILTER ( http://davidshelton.de/blog/?p=163 ) filter it to anaglyph.

But the video's are not running simultanly, and in fullscreen mode not very smooth.

Can somebody give me some hands to start?