Answer for Masking questions

Hello, Gery. The masking on the video was to avoid coating the other section of the hood, which we were going to use to demo another coating, for another video. You would not normally mask the hood in that way.
For plastic areas, there should not be staining unless it is faded, wherein it would make it glossy. Please do a small spot test, to verify, before applying to whole area.
Thanks for your question.