http://www.twitch.tv/lirikk/b/325990907 around 30 mins and at the hour you can see the hacks op is talking about... Someone released a VIP hack and it quickly spread like wild fire on forums....
Yea 1.7.1.4 zombies were god like... But now it isn't so bad!! You can be about 10 ft away from them while prone and be fine, just don't move or accidentally stand up.