I think they were going for more of an authentic look rather than a polished look. What they are showing is more closer to what you are likely to see from your users.
If you're not taking simple, easy steps to improve your presentation, what you're being isn't authentic but sloppy. You dress down in old jeans and a t-shirt, not the shoes you work in the garden with.
vince, i think you're missing the point. the video stream is an integrated part of the product
Exactly, I don't think most participants will spend hours in front of a mirror to "casually dress down" before testing your product (nor do UX researchers, who are presumably the primary target audience care).
The entire application is centered around recording the users while they are really using your application. Nobody really uses a tripod on their phone and I would doubt you have the best lighting when you're just searching for a song on spotify.