In my opinion, what makes this closer to sexism than bad manners is the fact that the same person seems to have conducted himself with good manners for the rest of the event when talking with the male members of the panel.
https://youtu.be/Er7qPv8jsZo?t=27m9s
So I think you're looking for grounds for sexism accusation which aren't really there.
Further more, there's nothing stopping her from stepping in and giving her views at any point, as other members of the panel were doing from time to time. If she's too shy to jump in, please don't blame that on the conduct of the other participants.