I'm a mortal.....just one with lots of practice.
The heat is just used to reduce the viscosity of the resin when wetting out the multiple layers of material in the flap. I don't use it for the rest of the layup. If you watch the video closely you can see the resin working into the bubbles and such.
This mold has a resin trap. As the bladder compacts the layup there is less room for epoxy so it gets pushed out of the mold. It migrates .25" along the flange and then goes into the trap. The resin doesn't go past the trap. When I'm cleaning the flange I'm only cleaning the area outside of the trap. This makes cleaning up the mold much easier after the part is made. The resin between the part and the resin in the trap usually comes out with the part. Clean up is then a breeze. If I forget to clean the flange then I have scrape and vacuum it off. Not the end of the world but more timely than cleaning it off while it's still wet. The vinegar doesn't affect the Frekote mold release.