NPC's walking/noticing like this

hey all!
It’s been a while since I’ve been making games with flash, but today I had the urge to do start doing it again. I’ve made a lot of games in the past year but the A.I. for my NPC’s were always a bit stupid. I could get them to walk and notice my player and shoot etc, but the A.I. in this game is very cool:
http://www.teagames.com/games/paintball/play.php

I don’t know if there is a samiliar thread about this specific movement because I couldn’t find any. If there is, then I apologize in advance.

Could anybody give me any good tips/ideas to make my NPC’s move kinda like these?

Any help would be very appreciated!! :player: