How can I embed a video at top of post and use another thumbnail image on the homepage?

When you use a video for a post’s Featured Media, it doesn’t create a thumbnail image on the homepage. But there’s an easy way to fix this.

You can paste the video embed code into the body of your post, in Text Mode. If you paste the video in the top line, it’ll display at the top of your post just as if it was set as Featured Media:

Tip: When you grab the video embed code, it’s best to customize the video size to 771px wide if you’re using the One-Column (Standard) post template. If you’re using the Full-Width (no sidebar) post template you can embed a video of up to 1170px wide.

What about the Homepage Thumbnail?

Now that you’ve got your video embed code pasted into the top of the post, you can add any image you want as the Featured Media. Just make sure in the Featured Image screen to check the box to “Override display of featured image for this post?”:

The results are a nice big video at the top of the post page:

And the image of your choice displaying as a thumbnail on your homepage: