I don't know. My motors do fine with water in them. Some guy on RCgroups breaks in his new brushless motors by running them underwater! I don't know how it doesn't short, but I've flown in the rain (here we get quite a bit) before and still have the motor(the one I used on my Cabon B-1 scratchbuild)
I haven't bought it yet but it should work on everything. ESC, OSD, Servos, ect. It isn't oil based like WD-40 so it wont mess anything up. All I would be worried about would be dust and grim sticking to it.
That technique comes from the brushed motor days, where to the brushes could overheat without cooling for the first couple of runs. On brushless motors, the only parts that rub together are the bearings, which should be greased appropriately out of the box and shouldn't need cooling to run.
The bearing in those motors are sealed. And they are horribly cheap. I'd put money on that or on the edge of a stator being bent and rubbing on the magnets. You can check for that by coloring the end of the stators with a sharpie, running the motor, and checking to see if the sharpie was rubbed off of any stators. If it was, you can sand or gently tap the raised portion down with a hammer.
Oh Yes and a tip for the first FPV, know your surrounds! take a walk around to get an idea on how far apart things/places are...I fly in a park and kinda know that by flying LOS by the time I'm over the big tree over there in need to turn, If I line up the approach between those two small trees I'll land at my feet etc...