Remove thumbnail

Hey guys,

I’m trying to figure out how to remove the thumbnail (featured image) view from the post displaying on the main page and show the full picture with a small description.. Basically i want the readers to view the large image on the main post without going into the post itself to see the large image

Also the same fore videos…
Right now for videos.. I upload it and then post a featured image ..
I wish to upload a video and show it right on the content main page…
Please advice…

Thanks in advance..