Q: Why don't my video textures play when streaming?
A: This most frequently occurs in projects with legacy components or textures that have been brought along through multiple iterations of the project.
In most cases this can be fixed by removing the texture and associated video files from the project and rebuilding them. Follow the Unreal steps for adding a new video texture when rebuilding the video textures.
NOTE: UE 5.x requires use of their Electra player for video playback in pixel streaming, and is strongly recommended for use in UE 4.27 as well.