Anyone can put anything on the internet.
And frequently do. Ironically, the best piece of advice I can think of for preventing ingrown hairs wasn't even mentioned: don't shave too close. I would hedge a bet that anybody who had to go to such great lengths as shown in this video to prevent ingrown hairs is probably using an overly-aggressive shaving technique. Either that, or they have really curly hair that makes them naturally more susceptible to them.