An actual solution to this would be to alter how the "room lockout barrier" works. Either it doesn't go up until after people have finished watching the cutscene, or the single person who was watching it gets a 'free pass' through the barrier.

Alternately, set it up so people get warped into the boss arena upon completion of the cutscene? It works that way for the later scenes in the Praetorium.


(And yes I know that the original post is most likely sarcasm but it is, nevertheless, a game-design problem that you can get locked out of the final part of the raid because the cutscene is longer than the lockout time on the barrier.)