I don't add comment to videos and rarely even read the comment left by others. But it is no surprise that some comment is richly textured. The Internet is more than twelve miles across at its widest, so there is a lot of room for complete fruitcakes to post garbage. Much or all of it is best ignored.
I have used some of the better Helmetcammery in the past to make points about riding in traffic to my offspring. Some of it is excellent for this. Gaz and one or two others others are extremely useful and helpful.
What is odd (and odder still that they have the vocal support of many members here) is that there are some complete Far Quits who start their own channels and post footage that makes one cringe. These are people who'd get angry about a paper clip that was the wrong colour.
Yelling "Pull over!" at badly driven cars like one of Macbeth's helium-sucking witches or raging around handing out tickets through car windows for fairly innocuous infringements are disturbing enough behaviours even before the cameraman decides to share them with all of humanity. Some at the crunchier end of the Totally Barking Spectrum seem almost desperately keen to publicise their disturbing instability.
It is all good comedy at one level, but these shouty and self-appointed Federal Marshals of Hoo-Gives-A-Fookery damage the image of cyclists and might be argued to undo some of the good work done by their sensible, moderate, socially competent brethren.
If I had a YouTube channel, I would not allow comment. I am always right, so dissent or disagreement are a waste of time.