Post Category not showing embeded video thumbnails.

Hello all,

I have recently started using Sydney as a new style on my website and I am unable to view the embedded youtube videos when viewing posts via post categories, on my old theme it used to look like this: Embeded video thumbnail in post category (old theme)

But now it looks like this: New theme post categorys

And I was wondering if there was a way I could make it so I would be able to view embed videos when viewing posts via the post categories.

Many Thanks.