you mean the pulse?
you take the clip you want to add the effect to, then duplicate the clip and place it right above the first in a second timeline, lower the opacity to 50 (or around there, depends on how visible you want it to be) and then go to the pan/crop window on the clip on top and if you want it to pulse outward make the clip zoom in... if you don't know how, make a diamond mark at the start of the timeline and then make one at the very end and zoom shrink the little rectangle box thing on the picture (great description lol..)
anyways if you want it to pulse inward, do the opposite.. make the clip zoom out
you can also fade the top clip out.. or not... depends on what you want
or that's how i do it anyway, so hope that helped