I can respond directly to this, I’m a former VFX industry person and still fairly well connected.

The the former you suggested. Background plates and the like. The lack of actual creative direction tools, trite visual style, lack of consistency/repeatability and complete inability to be edited or adjusted easily make it a non-starter for most tasks. Compositors are fast, LLMs are slow at that scale. There are tools like ComfyUI that sit in the “we’re running experiments/useful sometimes” category.

Loads of ML tools are in use and incredibly handy, but fit into that tool category, but actual wholesale video/image generation is not that prevalent, no.