Found it. But the video is now gone!
As are some other videos that I linked to. That's too bad. I'm going to start listing the titles from now on so we can find them if someone else later posts them.
Original post: Here is(was) actual video of the engines being painted in the factory. Notice the water curtain for the overspray. And notice the third guy painting the one engine blue (or black) and the next one yellow.
At 12:53 in
https://www.youtube.com/watch?v=yotAogMph68 (now 404)