Hi there and welcome!
It's pretty normal to have 16:9 cut-scenes in games. On multi-monitor, I'm used to the outside monitors fading to black for cut-scenes, and then coming back to life when the game resumes.
If you want to try to fix it for each game, you'd need to look at the Master Games List (
http://www.wsgf.org/mgl) and search for the game in question, and see if someone has made that fix for that game.
As it's not something that is usually considered a problem, I am not sure how many games will have this cure for you. All the best!