True, but only part of the equation. Using another person's likeness for commercial gain without their permission can be highly problematic. So, if he's interviewing people on the trail, or just recording their antics no issue. It's when those videos get posted to a monetized YouTube channel and the poster gets paid without the consent of the recorded third party there could, and inevitably will be, letters from lawyers.
Not really! Watch a lot of Youtube and tell me that the filmer gets a release from a hundred people on a street corner for example.
You think paparazzi get releases from every famous person they snap? Do Paparazzi get paid? Yes