Is there a way for the A1 crawler pick only one video per page?

If A1SG can identify there is a page containing only a single specific video, A1SG will usually be able to pick that page only for the given specific video when building the video sitemap, even if the video itself is used and referenced from other pages.

The "association" scoring algorithm takes various things into account including e.g. video/page uniqueness and url/path similarity between videos and pages. (But it is not a simple matter and therefore not always perfect.)

What is your website 3dloco + can you give example of a video URL not associated to the best page URL? You can also email support directly with this information (From your description it sounds like multiple videos are associated to the same page in the video sitemap, but that would not happen if A1SG could identify a unique page for each video.)