The shooter real name Scott Beierle was part of the alt-right movement called “Incel”. Incel are exterme misogynist who view woman as the root cause for their failures.
In the video he said women were capable of “treachery” and “lying.” He spoke aggressively about women giving him their phone number even when they had a boyfriend and how angry it made him. He also mentioned a girl who cancelled dates on him. “I could have ripped her head off,” he said.