Some inaccurate information in that video:
- He says disc wheels are heavier. It is the opposite; when you don't have to rely on the rim for braking, the wheels can be made lighter.
- He says rotors constantly rub the pads; I have been primarily on disc brake bikes for the 4 years, and I have never had any sort of persistent pad rub, ever. Sure, sometimes they rub for a few seconds after heavy braking, but that is about it. I also work as a mechanic and don't hear our customers complaining about brake rub (and we have some picky ones).
- I ride in the wet and mud (gravel) frequently and brake pad contamination is not as big an issue as he made it out to be. On the other hand, I have done rides in the wet on rim brakes and carbon wheels and damaged the brake track because some grit got stuck in the brake pads and did a number on the rims.
To be fair, there is also plenty of accurate information in there
Rim brake parts are indeed cheaper and groupsets are about a pound lighter.
To me, the biggest benefit of disc brakes is that it allows running very large tires in the frame. The Specialized Cruxs of the world wouldn't exist on rim brakes.