> want, it isn't going to create the video I want from a prompt when I've already got the video clips I want to edit.

You act as if there aren't a bunch of non-AI video editing apps that try to do exactly that, nevermind AI apps that try and do that.

> I don't need to edit clips of people with 7 fingers

There's more to AI than image generation (and 7 fingers isn't the same problem it was 6 months ago). Specifically, picking out the important part of the clip, adding appropriate captions and music from the AI processing the video.

> I need to edit my family vacation video

Yes. What do you think an AI enhanced video editor would do? Be Photoshop? Editing the family video from hours down to a digestible video for sharing is a time intensive process, and while I'm sure you enjoy it, not everyone does. A "Make vacation video" button for those people for whom that's a chore and not fun, and don't remotely care to be semi-professional video editors is the target market for a program with a feature to find decent photos and snippets of video from a giant pile of stuff, and arrange them into something cromulent.

As far as state of the art for generated content, a cousin of mine used AI to take a still image of the extended family at dinner with their hands under the table, and turn it into a convincing video where everyone raises their hands and waves (with the correct number of fingers, in case that needed to be stated.)

Anyway, to answer your question, the react library backing this for building your own to drop in is called Remotion. If you'd rather a different video editor, https://omniclip.app/ was mentioned as being an open source no-upload video editor.