Most "AI video" tools hand you clips and leave the editing to you. HeyGen's Video Agent doesn't. You give it one prompt and it returns a finished vertical video — presenter, captions, motion graphics, cuts already made.
I spent a morning pushing it, and the interesting part isn't the generation. It's the revision loop.
What actually matters
Your starter prompt sets the ceiling. "Make a video about AI tools" gets you a generic video. Naming the audience, the single takeaway and the tone gets you something you'd post. The agent doesn't fill gaps you leave — it guesses, and it guesses average.
Revise scenes, not the whole video. The first output is a draft with a scene timeline. Asking for a broad change ("make it punchier") regenerates everything and usually loses the one scene that worked. Scene-level requests keep what's good.
The digital twin is the deciding factor. A stock avatar reads as stock. Your own twin, with your voice, is the difference between an ad and a video people watch.
Where it stops
Pacing. The agent's cuts are competent and slightly slow. Two minutes in CapCut tightening the first three seconds does more for retention than another regeneration.
The full walkthrough covers the setup, the starter prompt I use, the scene-revision phrasing that works, and the export settings.
— Tech4SSD