From Canon USA:
Thank you for using Canon products.
We have identified a phenomenon which prevents movie files shot using Canon EOS 6D Digital SLR Cameras from being played back on YouTube.
EOS 6D Digital SLR Camera
- While we continue to investigate this phenomenon, please follow the instructions outlined below to upload Canon EOS 6D movie files to YouTube. After our investigation is complete, we will make an update to this announcement.
- Download the movie file(s) from the EOS 6D camera to your computer.
- Start ImageBrowser EX, an application bundled with the EOS 6D.
- After selecting the movie file(s) to be uploaded, select [Edit Movies] in the [Edit] tab from the menu bar of ImageBrowser EX.
- “MovieEdit Task” will start. Save the movie using the [Save] menu on the screen.
- Upload the saved movie to YouTube.