Given that

• there is no auto-preview / download of youtube thumbnails for posts
• the post URL must be the youtube link; uploading an image replaces the URL with the one if the image, so no bueno

What is the format to embed the thumbnail of the youtube video (downloaded manually) in the body of the post and also link it to the video itself?

The reason I’d like to include a preview is that I find it hard to find and click the external link for a post. Sometimes I don’t even realize it’s a post with a link (both in the listing or after opening the post) - Reddit apps (at least in the 3rd party Slide app that I used) made it clear what type of post it was by clearly specifying Video / Image / Link / Self.text etc