For me, it would be worse - I'd be distracted from my own story by paying attention to the other story, or even worse, I'd start copying the movie instead of writing my own stuff.
Took the words right off of my keyboard. It's not something I could concentrate or write through. There are folks who will say no worries because my writing voice is so strong or my idea is so fierce and fixed in my head or my characters and I would sit together and watch the film or blah, blah, blah. Yeah... right after you finish your facebook post about how you climbed K2, had tea with the Dalai Lama, and then zipped to South Africa where you used two great white sharks as water skis.
I do sometimes write while watching a movie/Youtube or even playing video games. Naturally, it is only the illusion of productivity, since it nets me about one line per hour.
Not so fast, now... Sometimes writing while watching TV shows or a movie (or listening to music) can be very helpful. Sometimes you hear a particularly nice turn of phrase, or something as simple as a cool word you didn't know. When I played guitar for a living (before my retirement) I spent a lot of my off- time sitting on the couch and picking while watching the tube. Plenty of music is played as background for TV shows and movies - duh - and I would find little melodic phrases and cool rhythms in the background music or even in the speaking voices of the actors. I wouldn't copy them note-for-note or beat-for-beat, but I would find inspiration in the delivery and phrasing. I apply the same to my writing. I won't copy a line, hopefully, but I will be inspired by the tone and rhythm of the writing. I find it works especially well for non-fiction writing or for scene and setting development in fiction. For me, anyway.
When I was eleven years old my parents bought me a portable tv set for my birthday it had some crazy addition on it - a cassette recorder - not a vcr, just a cassette player for tapes. I guess it was for taping off MTV or something. I used to tape movies t0 listen to them. That was actually kinda fun no visual just conversation, music, sound effects. I used to listen these tapes of movies a lot back when I was fourteen and writing. I used to watch movies but it does get distracting. Once I even started to type the dialogue that was being spoken because it was so similar to watch was going on in the scene.
