If you sit in the back of a pick up truck how do you hear the movie IF it plays through the radio in the cab of the truck that has no back window that opens into the back of truck?

Yes. You can bring your own radio. Also when everyone there has it on the same radio station. You can hear the movie outside of your vehicle.

Portable radio

There you have it, you got your answer. That is correct

Your car stero

We used a Bluetooth speaker and are Android phones Radio Station App and we heard the movie great just recently went to see Godzilla vs. Kong and Mortal Kombat loved it