middle tennessee state university george davon kennedy was arrested and charged with sexual assault tuesday night .
police claim he was one of the participants in a gang rape that occurred in panama city , florida in march .
troy university students delonte ' martistee , 22 , and ryan austin calhoun , 23 , were previously charged in the attack .
police in troy , alabama , found the video while investigating a shooting which ` shows two men raping unconscious woman on florida beach '
authorities say hundreds of people walk past but do n't intervene .