I don't see or hear any "children" in this video. These are adults who are unwilling to grow up, in particular the guy who acts as a leader, moderating the meeting and obviously enjoying to act out his resentments towards his parents (or proxy adults).

Parents treat their children like children because they are their parents. Only when you can prove to your parents, by means of your later adult life, that you can take responsibility for yourself and your life, will they begin to take you seriously. As long as you complain to them about their mistakes, about their evil deeds towards you, you are signaling to them that you are still a child. So they treat you like one.

As for parents who where brute fuckups and sexually or otherwise abused their children, it's better to cut off your attachment if you can sense that they did not and will not work on their own maturation (although, once you are adult they neither can beat nor fuck you, that shall be obvious). It's useless to hope for their bettering if you can already see that they won't make efforts. If you can forgive, do it. If you can't, then don't. It would be of no use to tell them how much you hate them or spit on them, they will gain no insights from that.

Nobody can make you do one or the other.

Now, to follow the advice from that moderator, to puke yourself out and to direct all your hatred towards your parents, that has some components:
a.) is to copy and paste the dark parts of them, and the older your parents become the better victims they will be for their sons or daughters. Who themselves do not notice that they fluently made the transition from former victim to present perpetrator. That is well known psychology and I am astounded that you don't seem to know that.

b.) still signaling your dependence on their reaction. If hatred - as a very strong emotion - shall be directed at your parents, you still are very needy for their judgement of the situation. You either hope for a strong reaction (rejection, accusation, ridicule etc.) or for a miracle (like them kneeling down and begging for forgiveness).

c.) you want to punish them.

Did you not say that punishment is nothing that works? I would agree when this disciplining of either children or parents comes with strong emotions of malevolence. It's of no use and only harms all people within this dynamic.

Some family dynamics cannot be resolved. They remain unresolved.
Many are in the middle though and have a somewhat decent relationship.
And also many have a good relationship with each other.