Guys, do not use self-illumination as it ALWAYS generates some light and casts it into the scene, and you don't want that. Additionally self-illumination is sampled just like GI, so it may be noisy, as opposed to lights (and Corona Light Mtl) which are sampled in a much more efficient way.
So don't use self-illumination for this.
The proper solutions are:
Option 1) Plug an environment texture into your glass material's Reflect BG override and Refract BG override slots
See the bottom of this guide (it's a little bit outdated, sorry, we will fix it ASAP) -
https://coronarenderer.freshdesk.com/support/solutions/articles/5000501978or
Option 2) Create a backplate (like you did in the video), but use a Corona Light Material with "Emit light" option disabled. This will automatically disable light generation and disable shadow casting, so you don't have to touch the 3ds Max Object properties and at the same time it does not block environment lighting. It was designed exactly for this purpose.
See this guide -
https://coronarenderer.freshdesk.com/support/solutions/articles/5000515605Also, using the rayswitch material / map is not necessary here. It does not influence the reflections appearing in the material. It influences how the material appears in other reflections. (e.g. if you can make your glass panel appear red when reflected in other objects)