JoyChang

Not sure if this one is what you need. It's from the official blog post.

Tried to use the flag counter on an unpublished cahce, but it keep showing "Remove all images hosted on a third-party website to save changes." Not able to save the cache page until I remove the flag counter.

Have you check if the video is public or not? Private videos will not be available to play. Or, you may check if you paste the correct URL, it'll be like this: "https://youtu.be/_video's_code_here"

I've same issue here, some android phones could play the YouTube video and some couldn't (like mine). It shows a broken file icon when I tried to play the video on my phone. But then I tried to update the YouTube app to the newest version, it works for me now.

A flag from Taiwan added.