Well, that video is entertaining; like most of the mighty mods videos, but as far as it being an answer...it is NOT. 99% of the cooling of the intercooler is done by the fins between the compressed air channels, and the effectiveness of the intercooler is all about the surface area of those fins. If you think spraying any type of "insulation" is going to increase the emissisivity or radiation (especially an etching primer followed by paint of any color), you aren't thinking about the problem correctly! As long as you contain the paint to the front or back side of the compressed air channels and not to the cooling fins, it probably doesn't make much difference, but keep any insulating material off the fins.
Having said that, there may in fact be some type of coating that one could apply to the fins that might enhance the surface area (think a pebbling effect), while not insulating the fins, but I'm not aware of such. But if you think painting an intercooler black is going to help anything but stylishness, I'm going to disagree.