The Black Screen issue has been fixed in Unreal Engine version 5.1.0. Please update your project to UE 5.1 as soon as possible. The plugin should work well in 5.1.
Check this fix in MoviePlayer module: https://github.com/EpicGames/UnrealEngine/commit/833a1966f7b96c15dbf2aff7a029476fde06edc4