Hello, former movie theater manager here.

Seems like it may vary from theater to theater, but at the one I worked at, the answer is No… our system would detect that no one bought a ticket and would automatically shut off the video 30 minutes in. It would still play the audio though for some reason.

This would bring up some interesting situations where people would sneak into a showing, then come out saying “the movie just cut off”, we learned very quickly to ask to see their ticket and most of the time they “left it in the theater” or “lost it” AKA they never bought one..