Ostadar's hack in house glitch

Hello, im a warinc gamer and i would like to ask how this guy: gamertag : Ostandar/Ostadar can glitch through building and fire from there? anyone? like in crossroads the building beside Z flag he hacked there and was able to score 49/0.

i used vegas lite hack and shot that moron 20 times till he quit, followed him after the game ended then repeat. marvelous. then he chatted on world chat "hacker" lol.