2.80.75 - Pack into blend file not packing images referenced in materials

I have a couple of objects in scene which are “displays” and show different, pre-compiled movies frame by frame when rendered.

I need to pack all external data into the blend, but it is not doing this. The movies are several hundred MB big, yet the packed file is only 1MB. I can only imagine this is because the movie frames are selected for each frame in the materials tab.

Does anyone know how to fix this? I’m sure old versions of blender this didnt happen and everything just packed.