I was slightly amused just now watching a documentation on people with dwarfism.
They showed one child getting shoes custom-made, and the shoemaker spoke with a southern accent. (Austrian? Bavarian? I'm not good at pinpointing regionalisms.)
He seemed to be self-conscious about the fact, since a couple of times, he repeated himself in a slightly more standard phonological form, as if he seemed to feel the need to speak as standard a German as possible on camera, even though the first version of each utterance was perfectly comprehensible to me—merely obviously regional. ("Heechstens—Höchstens" and "Auf jeden Fuj. Do wird sich net viel verändern—Da wird sich sicher nicht viel verändern. Ganz sicher nicht.") So he needn't have worried about being comprehensible to viewers from other parts of the country IMO.