Arbiter casts recall after EMP: http://www.youtube.com/watch?v=_uk7t35oM2s&feature=related

Could SC-engine gosus (for example Heinermann) explain, why it's happen? Is it a bug or regular behavior? If regular - why it's regular?

Thanks

If you look at the comment by gotriceandshrimp, it is explained.

Recall has 2 parts to it: the summoning part when you target the units and the teleportation part where they are moved to the arbiters current location. The arbiter cast recall on the target units a fraction of a second before the EMP hit, meanwhile the animation played out at the source location and then as the arbiter moved the teleportation part began and warped the units to it's present location.

I should have selected "regular behaviour".

You can move and recall at the same time. You just can't interrupt it by ordering the arbiter to move somewhere else.