Can you still see other players after they died?
Yes, all the other players stay visible with their disguised entities/mobs.
In that case, I assume that the developers of that minigame were just sloppy enough to not care whether you (the recording player) are visible to yourself. This is because you can't be invisible in F5 mode to yourself unless having an invisibility effect and wearing no armor/items. So probably the plugin just makes you visible to other players again.
If my theory is right, there's nothing we can do about it.