It is referred to as the cathartic effect hypothesis.
Explanation:
The TV shows or videos that display aggression on the screen result in stimulating the urge of the viewer to show aggression. This urge sometimes culminates in actual aggressive action in real life too.
In this manner, the urge to be aggressive is finally released by repeating what was seen on the TV or in the video. This entire process is known as the cathartic effect hypothesis. Bresin based his research on this theory that implies there is a "healing and anger-reducing affect" which occurs through aggression.