While I have some shred of sympathy with the argument in this case, I have issues with the cry of sexism.
In it's purest form, sexism is the belief that a person's sexual characteristics are determinate of their ability in an unrelated area. For example, that women are less able in business or that men are less able to care for children. In this sense, the vast and overwhelming majority of human beings are functionally sexist. Even if they would not make openly sexist comments, most people still unconsciously accept and perpetuate the existence of 'natural' sex roles. Virtually everyone is sexist, men, women, children. Everyone.
This is why, in general, people restrict the definition of sexism to cases where there is a clear and measurable social disadvantage to being seen as less capable in a given behaviour, for example a woman being passed over for promotion in favour of less able male colleagues or a man being excluded from a daycare centre.
What's being described in this video is not 'sexism against men'. It doesn't fit either definition of sexism (well, actually it does, but not in the expected way at all). It's about reactions to sexual violence, which doesn't necessarily have anything to do with sexism in the normatively understood sense. We react largely the same when men are violent to each other (as is the case in the overwhelming majority of violent crimes) as opposed to when men are violent to women. The issue is not 'women as aggressors', the issue is 'men as victims' - because those words are largely incompatible by design.
Now, on to the main point which I seem to end up pointing out on every 'Wah! Women can get away with violence!' thread. Yes, it is socially harmful in many ways that violence against men is taken less seriously, but it does not represent a general ordering of society against men. In fact, the same force which makes violence against men more acceptable also underpins large sections of male privilege, and that is the belief that men 'can take care of themselves', that they are tough, emotionally measured and derive credibility from sexual conquest rather then from sexual passivity.
So hang on.. if you want people to feel horror when someone assaults you or chops your dick off, then you need to give up the idea that you as a man should derive legitimacy from being seen as able to take care of yourself, as not needing the support or sympathy of others, or as always by definition being the 'active' participant in a sex act and of never being a victim (except in regards to other men, and then you're just a pussy). Violence against you will only seem horrible when you are willing to accept the same perception of weakness and vulnerability to harm which women live under every day.
If you can all do that, we will probably live in a much better world for it.