Please describe what you mean a bit more. I'm not sure I get it from the video...

Sorry, i thought it was clear. After removing the lamps in that area at 0:12 the background get's some white reflection in the upper left corner and at 0:30 you can see some dark lines in the upper right corner as well. The main problem I have are the reflection after destroing the lamps in a dark area.

Ah, I see, I thought this was an artefact of the video, but on second thought I have indeed seen this in-game before. Not sure what's causing this, but I'll refer it to the person who knows more about this.

Oh interesting, I haven't seen this before. Is it 100% reproducible? And does it look the same in-game?

It does look the same in-game, if it's reproducible I need to check later, but I can tell you that I used the egypt_cloud world lighting and egypt_inside_offset lighting for that part, if that helps.

I've seen the same effect in SeriousCsaba's test level for his crates resource, so it's definitely reproducable.

I reproduced the glitch but Shadoplay did not captured the layer, properties and history windows. After recording it with these windows, I was not albe to reproduce the glitch again, of course ._.
https://youtu.be/KxDd8rEnprs The glitch can be seen at 4:56
Lighting: system/default.env
tileset I used: garden_sand, env_egypt_inside, env_egypt_inside_offset, egypt_tile_inside_16, egypt_tile_inside_16_offset

Actually, I think it's some bugg with the default.env, cause I had these errors several times myself and it was always because of that.

That must be the case for the egypt_cloud.env too. The first video I postet had that glitch with the egypt_cloud.env