Hungry Hungry Felhounds/Ultralisk movement?

[Fulla]

Does anyone know how the movement is done on those games?

For those who played Uther Party on warcraft or Raynor Party on Starcraft. Any ideas?

Basically a unit chases players but runs in a constant circle around them getting closer, giving them more time to dodge and run away.
Difficult to explain but if you've seen you'll know.

Is it done with triggers or can it be done in data editor?

 

[Fulla]

Found a video to show the movement, skip about 15 seconds in watch the felhound chasing them.

[video=youtube;o4Ve60fvGbc]http://www.youtube.com/watch?v=o4Ve60fvGbc&feature=related[/video]