First, let my try to change the codec of the video files. Tried to get them reduced so no one would complain at size.

Actally, we aren't using alpha channels. We do use 4 skins and 4 materials, but like I said, I tested the terrains with 3DGS standard terrain shaders with the same problem. It's obviously something to do with terrains switching from A7 to A8. I will try to put an exmaple together, although our game code is complex and dynamic, I will try to pull out a level and sample source for you to look at. I will try to change the codecs on the Videos also to show.

Here is WMP versions of the movies:

WMP Terrain Shader Issue from A7 to A8

WMP Another example, different map

I will extract out a terrain you look at also, probably going to have to do that anway.

Thanks, Loco