Hey there,

I am really sorry for the delay of this reply as it is a public holiday for us here.

It seems like that is bug, I will log into issue tracker.

For now, you can download my attached file then replace into this file location :

JoomlaFolder/components/com_easysocial/themes/wireframe/story/videos/plugin.js

If other video format still having some issue, you can try modify on this file for temporary.