To answer your first question the effects of playing violent video games are children act more aggressive on the play grounds and violent behavior while still young and once the child has grown up.
To answer your second question video games industry's started a rating system because many people have been having concerns over how a child may act in the future if they watch and play violent shows and video games.
I hope this helps you... sorry i was hard to see your paper, it was on the opposite side of the computer