What is the truth?

The 5D III can shoot 6 fps, but if you shoot RAW, you can only shoot about 12-18 frames before the buffer fills up and shooting slows down to 1 or 2 frames per second. That only allows you to capture about 2-3 seconds of action at 6 fps.

If you shoot JPEG only, the maximum burst is somewhere between 65 and infinite, depending on your card speed. I think the infinite applies to UDMA 7 CF cards. This allows you to get a least 10 seconds and probably much longer shooting only JPEG.