Whats app button only sharing the link not video

This plugin is just designed to share a page/post url. It is designed to work within the WordPress framework, meaning it know about posts and pages. But it doesn’t know anything at all about the content of your page or whether it has images or video.

Facebook scans each page someone shares and extracts images and videos and displays them according to rules of its own. Most of the others just display the url.

There are probably other plugins out there that are designed specifically to share video or images, so they might suit your purposes. Or if you want something very custom, you could have it built into your theme so that it is aware of your specific content.

Cheers,
Sarah