3D movies on youtube aren't downloaded properly

I just tried downloading Hansel & Gretel from here: http://www.youtube.com/watch?v=x1e4KV1WbaY
There is a 3D option on youtube. When I try to download the movie I can't chose to download with or without 3D. And the video is doubled, with a separation in the middle of the screen. The two layers that are superposed in the youtube player are put side by side in the video file downloaded.