How does a video improve UX? It is much easier to find specific content in text than in a video, and easier to skim, to ascertain whether or not the content is of interest.
If a video doesn’t have captions or a transcript, any commentary is inaccessible to those with hearing impairment. If it doesn’t have a transcript which can be read by assistive technology, any visual content is inaccessible to those with visual impairment. Videos with soundtrack are also problematic if accessed in a shared environment, such as a library or even an office.
For a search engine to understand the content of a video (and therefore index it for use in search results), it also needs a transcript.
So the video itself is of little or no value, I’d say; the important part is the transcript.