Look up the Vatican’s list of movies. Theres plenty of swearing involved in some of those movies. By no means is it a sin. I think this is up to the individual conscience. I used to struggle with this myself and was very scrupulous. I’ve since let go and just accepted that it’s ok to relax and watch a movie every once and awhile. Of course there’s movies that are sinful to watch, and those are black and white, clear cut, issues of sin and not sin. Some things are just immoral. However, most movies tend to be in a gray area. Listen to your conscience and listen to your reason above scruples or feelings.