This is a bit surprising. When I initially looked through the live view settings on the Canon 6D , the layout, menus, looked very similar to the Canon T4i and Canon EOS-M Mirrorless Camera. On the 6D we have our face detection, Flexi-Zone, and the quick mode, & similar modes are found the T4i and M.
So when I go to start doing some head-to-head tests, lo and behold there is no “Engage Auto Tracking” feature on the 6D. What this means is that the 6D cannot auto focus track during video, and Canon has 2 cameras out there, both priced at nearly 1/3 the cost that can. Equally confusing is the fact that the 6D works with the new STM (Step Focus) lenses for quiet focusing, which was built around this whole idea of silent auto focus.
While yes, you CAN focus while recording video, you cannot turn the camera on to do it for you.
This is a little disappointing, because it is a really nice feature, and one would hope that for $2100, it would also be on there as it is for the T4i & Canon M.