Should I be bothered? Parents put Rated R movie in front of toddler

Its those old school spanish movies where its pretty much NC-17. I've come home a few times and there he is in bed with them watching these flicks.​I know my mom gets tired and doesn't play with him the whole time. She sometimes gives him the phone to watch some videos but he's watching the movie instead. Big screen right on the wall, so it's hard not to watch. It's always some sex scene. Today, it was some older lady in a thong stripping for some guys.​I mean he's 2 y/o and 8 months. How much does he understand? Who knows, I just knows that it bothers me and I've told my mom to change it when he's in there but of course she's in there. I will look elsewhere for babysitting I guess.​What do you guys think? via /r/Parenting https://ift.tt/2P1054K