Searching for AI video online returns four different kinds of browser tool, and they do not really compete with each other. Some generate video from a prompt. Some edit video you upload, usually by letting you cut a transcript. Some process a file and hand it back changed, with captions, a dub, an upscale, or the background removed. Some index a library you already own so you can search it. Which one you want depends on whether the footage exists yet.
Generation
Prompt in, clip out. The output is short, and it is new material rather than your material. This is the group with the fastest release cycle and the loudest marketing. If the thing you need already happened on camera, it is the wrong group.
Editing in the browser
Upload, get a transcript, delete words, the video follows. Browser editing has caught up far enough that a rough cut of an interview no longer requires desktop software. The limits are the ones you would expect from anything that runs on an upload: file size caps, render queues, and the fact that your source material now sits on somebody else's server.
Processing and conversion
Captions, translation, dubbing, upscaling, format conversion, background removal. These are single purpose, take one file at a time, and are the easiest to try because there is nothing to learn. Nothing here changes the edit. It changes the file.
Search over a library
The fourth group does not modify the video at all. It indexes what is inside your files so you can look for a moment by describing it. Most "AI video online" roundups skip this group, partly because the tools are usually sold to teams rather than individuals, and partly because the job only becomes visible once an archive is large.
The question online tools rarely answer
Everything in the first three groups assumes you already know which file to open. Upload this clip, caption this clip, cut this clip. That assumption holds while the archive is small. Once the material is spread across drives, cloud folders, and an old NAS from a previous vendor, the missing piece is retrieval rather than processing. No amount of captioning tells you which of 900 files has the shot in it.
That scattering is also why the fourth group works differently from the first three. The first three all begin with an upload; Vivu connects to the storage the material already sits in and indexes it where it lies, so the old NAS never has to be tidied up, consolidated, or copied anywhere. What comes back is timestamps with the context around them, which is an answer to the which-of-900 question rather than another file to process.
When you do not need any of it
Small archive, one project at a time, everything shot in the last month: a file browser and your own memory are fine, and they are free. The same goes for one-off jobs. Standing up a new system for a single deliverable is more setup than it returns. This category starts to earn its place when the same material gets reused across projects, when more than one person has to find things in it, or when the useful shots were filmed two years ago by somebody who has since left.