I can't speak for others and why they disliked the video but I think there are some things that can be disagreed with in her speech. I agree that she isn't being controversial and she is clearly trying to talk for the betterment of all and not just trying to victimize herself like a lot of militant feminists seem to do, but there are a few things that could have been explained better or I feel she is misrepresenting/wrong about:

1) She blames the male dominance of the smash community for making her resent other women in the scene and question their actual interest in the game.

To me this is unfair because this is just a thing many women are prone to do in general. They are competitive with each other. It is a natural inclination. Not every woman will fall to this inclination but it is something that many of us are genetically susceptible to. In fact, the same is true for men having rivalry with other men.

It's also silly because she is not taking responsibility for her own viewpoint of other women and instead is blaming it on the males in the community for making it feel like the norm to criticize women in that way.

2) It seems like she did like the extra attention for being female--until that extra attention was negative. She seemed happy that people focused on her being attractive or "angelic". Not that I blame someone for enjoying that, but in a speech talking about how gender imbalances and sexism are bad you can't just acknowledge the negative impacts of something while trying to ignore how much you like the positives.

To be more clear, my point is that she should not want extra attention based on gender either way but it seems like she was perfectly fine with being more noticed for being female only if it wasn't negative attention.

Either way she also fails to acknowledge that this is an issue of the ratio of men to women in the hobby rather than any inherent sexism in the community. By being rare you become a novelty. This is not something that can be blamed on sexism in a community as it is not the responsibility of men to make sure that women are as interested in a given thing as men are. Something can be said for how welcome women are in such a community but a key issue that is missed is that by ratio women are not more or less welcome in the community. It is just more polarizing how much attention they get one way or another. If someone likes you as a female they are more likely to really like you and if they dislike you they are more likely to be mean to you. But overall, they are not treated better or worse than men.

3) As shitty as some people can be about it, there is no denying the fact that a lot of women in gaming are in it for the attention and don't have the legitimate deep interest that men will have in gaming itself. Many of them are in it just for the community aspect rather than the hobby.

It is unfair to assume that every female is this type of gamer, but it is not unfair to guess that, based on certain observations/knowledge, a given female may be that type of gamer. I feel that most people fail to realize the difference between those two things and the fact that one of them is not sexist.

Basically all of this comes together to show that she makes the same mistake in understanding parts of the issue here that most people do. It is not necessarily misogynistic or sexist to understand and apply the knowledge of certain facts about women in gaming. As long as you are not understanding or applying it incorrectly.

Though of course, I wouldn't downvote her talk because I think the main point of hers is important. That we should try to educate those that may be biased in any community against a sex rather than try to villainize them and push them away. By doing the latter you only teach them that they were right to want to segregate themselves and their viewpoints. By doing the former you get everyone to understand each other and more accurately accommodate every despite our differences.