twirly, I just wanted to double check if that was the right demo mission in your link? It's a nice demo of paradropping from an MV22. I did enjoy it 
Here is one possible way of handling the distance problem with many units. First create a trigger that covers the area where the chase can occur. Set activation to side of the "catchers" such as OPFOR. Name the trigger, I'll call it "trgPursuit". In the condition put:
Code:
{ escapee distance _x < 10} count list trgPursuit > 0
Put whatever you need in the On Act. You may want to use a hint to test it first.
The "list trgPursuit" returns all activation units (like OPFOR) within the trigger area. "count" used in this context is like a forEach, and will compare each OPFOR's distance from the escapee, and if it's less than 10 meters, it will return a 1, thus activating the trigger.