It's in the 3rd video right near the end. He says:
I don't think we would ever do a game experience like Skyrim on one of those [mobile] devices.
His reasoning was that he doesn't like to play games on a mobile device that could just be done better on another platform. He likes games that are tailored just for mobile devices, that take advantage of the system.
And he didn't lie, those "Travels" games are not like the other Elder Scrolls games, and like Antibody said they weren't developed by Bethesda Game Studios.