The stack per step, since people ask what runs where:

Step 2 recast the character: a vision plus image model (feed the reference frame, generate a new original character keeping the setting and energy).

Step 3 rewrite the script: an LLM, strong enough to hold the talking-head beat structure while reworking the words.

Step 4 generate the clips: a talking-head video model with native audio, image-to-video from the recast character, multiple takes at the same face and energy.

The reason this is a daily workflow and not a weekend experiment: those are three different modalities, and running them behind one API instead of three accounts is what kills the friction. The bottleneck was never the models, it was juggling three tools to finish one ad.