Yup, in 2012 I was writing web video players and ad-serving platforms for a video streaming company. It was all Flash, because there were no real alternatives.

Yup, in 2012 I was writing web video players and ad-serving platforms for a video streaming company. It was all Flash, because there were no real alternatives. HTML5 was just kind of starting but HTML5+Video+JS did not allow to develop logic as complex as what AS3 provided.