Video thumbnails in homepage not showing

Hello ,

I am using this theme for my website. I do not know any coding so I hope I will find a way to fix this without coding. I am having trouble with my video posts. I see the video showing in the homepage once I post it but there is no thumbnail. I downloaded Video Thumbnails plugin hoping that this will fix it. The plugin would find an image for the video and set it as a featured image and I could this way see the thumbnail in the homepage. The problem is that the image was also posted right above my video in the video post. I do not want the image to be there, but only show as thumbnail in the homepage. Anyone having the same problem or knows how to fix this?

I would really appreciate it.
Thanks