Social dynamics often make it so that "nearly all male" is actually not that different from "male only". If you have better ideas about fixing the inequality, a lot of people would be very interested.

I haven't watched your video, but "this female only conference is a good idea" does not mean "all female only events are always great ideas".

A bit of side note, but in the video the organizer give a few examples of profession that the girls can become from studying science and the first one they mention is veterinarian. When asking the girls themselves, they too say veterinarian as the reason to study science.

Veterinarian is a profession which got around 90% women and only 10% men, with a trend that predict all women and no men in a few years. Kind of ironic example of gender equality activism.