Well, I have all of the equipment they used (even a laptop with that very software), except some piping and thermistors. As much as I respect MCM and have watched all of their videos many times, I'm pretty skeptical about the emissivity physics. I'll read into it though as it's something I've never studied before (even after studying thermodynamics last year)Flushing the heatercore is a fun job, I did mine and it was night-and-day difference how much heat I was getting out of the vents afterwards, to the point I worried about turning it on with the windscreen frosted incase it cracked
Your last post reminded me of this youtube video I watched years back too (youtu.be/f1QL9veQaNg) as a way to test how much heat each can dissipate. The summary is that they're painting intercoolers black in the video, which increased the amount of heat they scrubbed away stationary by quite a bit, but then a video debunking it showed that the extra layer of paint actually made the performance worse while the car was moving, defeating the point since the car is never under boost while idling anyway. But the set-up is a good one for working out performance of any radiator or intercooler using the calculations in the video. If you have a few radiators that fit and you need to work out which one scrubs away the most heat, you could try a similar set-up with a heatgun, a bit of plumbing and a rad fan to simulate wind moving.
edit: Hmm, I guess I've never considered how materials give off heat, only how it's absorbed (where the difference between matt black and reflective silver makes sense).
editedit: Seems more like the paint is what's responsible for the temperature drop, more so than the colour. From what I've been seeing, emissivity is more about the material on the surface. If that's the case, if any paint has the same ability to emit IR radiation, the colour would only effect the way it absorbs radioactive energy, so I'd go for something light. Too bad they didn't test black and white paint, in and out of sunlight. a video
edit³: Now I know why I was skeptical. The radiator uses air convection to dissapate heat, not radiation. EE's response to MCM: here