If you’re having trouble getting our 3D videos to work correctly, you may have to disable HTML5 in your browser.
For Chrome, you want to add this plug-in: Disable Youtube™ HTML5 Player and then, just to be sure, you can do the belt & suspenders thing by following the instructions in this video: http://www.youtube.com/watch?v=yoNfZHwfFOM
For Firefox, use this add-on: Stop Tube HTML5, then try this:
To disable HTML5 player in Firefox do the following:
1) type “about:config” in the address bar
2) go to the “media.webm.enabled” setting and
3) change it to “false” by simply doubleclicking it