In regards to the first part of the video, people do need to understand not every bird is comfortable with being toweled and it is dangerous to be indecisive when toweling a frightened/agitated bird. You could injure them as they attempt to flee or fight if you don't quickly control them and/or receive a nasty bite yourself. Many birds these days are coming home from the breeder already used to being toweled and therefore do not have a strong reaction to it, so a lot of bird owners have never witnessed this level of negative reaction to being toweled (that or their vet has them wait in the waiting area while their bird is going through this so the bird doesn't make a negative association with the owner and the owner doesn't have to see their birds reaction).
Part of proper toweling technique of a bird who is not ok with being toweled is to grab them behind the head at the base of the skull, which can look like the person has grabbed the bird around the neck. This can appear rough and cruel, especially when the bird is screeching like it's about to be killed (which is literally what the bird thinks is happening) but it is the safest way to restrain and control a bird who thinks it's fighting for it's life. When we first got Kiwi and he had to go to the vet for examination or when we used to take him somewhere to be groomed, this was about his response to toweling for years until we started working with him on it at home. It's the response my moms amazon still has after decades of vet visits to being toweled. Trying desperately to escape being caught, heartbreaking screeching, fighting back as hard as they possibly can, that look the bird in the video had when released of pure unadulterated terror... It's hard to watch but not necessarily abusive as it allows for safe restraint of a non-compliant bird so they can be examined or groomed.
I am NOT defending the video, as the second part instructing people on how to teach a bird to step up leaves much to be desired and she appears to have hard clipped the poor baby, just explaining a bit more about the toweling technique used.