oEmbed 404 errors when trying to use embed block

Question

When trying to add a Youtube Embed Block in the Gutenberg editor, I'm seeing these 404 errors in the browser console:

GET https://example.com/wp-json/oembed/1.0/proxy?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D[youtubeid]&_locale=user 404 api-fetch.min.js?ver=3.1.2:1

The block returns this message:

Sorry, this content could not be embedded.

I've tried on multiple sites, different themes, turning off all plugins, etc. Can't seem to find anything on this.

Other sites I manage work fine, so it really seems intermittent.

I did a fresh local install (WP 5.2.1, Twentynineteen) and it didn't work there either.

The Vimeo embed DID work though.

I'm not seeing any errors in the WP debug log or the php logs.

Answer 1

Answering my own question...

I figured it would be something simple. I had assumed that the videos I was trying to embed had 'allow embedding' activated. They didn't. When you edit the video in Youtube Studio, go to the "Advanced" tag and click "Allow Embedding". It's the only way a Youtube video will show in the Gutenberg YT block.