This is not kufr as long as he is denying with his heart but this major sin will eventually lead him to kufr as he is watching it and probably happy and enjoying it.

Shaykh is it kufr to participate in a video or a presentation in which someone commits kufr, if you disapprove in heart and say something against it after? Many watch films etc with kufr in (even if they don’t watch kufr bits) but approve if non kufr bits but are these other bits kufr because the actor is participating in a film with kufr?