(Note: I’m @bartekkustra - I created new account a while back)
There are two ways you can approach this:
Instead of using custom lightbox you can use Webflow Lightbox. I noticed you’re using Collection List there to display those, so feel free to check the community-made Dynamic Lightbox Code:
That way if you close the lightbox the video will just stop
The other way is - instead of using VIDEO field in Collection and VIDEO widget in Webflow - to build custom VIMEO player inside of your custom modal. There are great docs on that here:
Having that done you can then access the Vimeo Player SDK methods (https://developer.vimeo.com/player/sdk/reference#about-player-methods) that will allow you to play/pause the video. You’ll be able to call those by simply attaching a custom code to the closing icon of your custom modal, eg:
Hope this helps!