You only need to watch the first 3 minutes of the video to have it explain what an Incel is. A short transcript is below

"the psychology of these so called incels is a conglomeration of aggrieved entitlement learned helplessness and self victimization. They refuse to accept that women have the right to choose and selective about their partners and that unlike earlier eras they now have the power to use their own preferences as a guide before starting a relationship.

An incel does not accept this and therefore does not accept rejection nor the inevitable anguish that follows rejection instead they turn those unwanted feelings into blame and hostility seeing women as shallow and cruel"

The remainder of the video is an interview with Alek Minassian, an incel who comitted the Toronto van attack. https://en.wikipedia.org/wiki/Toronto_van_attack

The interview shows what an incel really is. Deceitful unintelligent degenerates. The interrogator does an amazing job at breaking down what happened and getting the incel to unintentionally reveal everything.