Gridframe theme video not working

Hi.

I need help with the free theme called Gridframe. I have created a video post and placed the video link to YouTube in the video URL input box below my post content.

The thumbnail shows up with a play symbol, but there is no video on the post-page!

I have the meta box option on, I have cleared history and cache, but still, nothing is showing. Can you help me, please?

Regards, Mike.