In the render settings for the movie sequence renderer
Add an Anti Aliasing node, then you can override it.
In the project settings, you can’t select MSAA unless it’s forward rendering
alternatively to overriding as MSAA, in the render settings you can just set the temporal samples really high (like 16) and just check “override”
Check this out:
Not totally convinced it’s not an alpha channel issue in the textures themselves but worth checking this as well.