Please see the three attached screenshots.
has created a ticket for this case here:
I am using the free version of the “FV Flowplayer Video Player” WordPress plugin to evaluate and for development before purchasing.
Uploaded an MP4 test video to Backblaze.com. The video is distributed by the Cloudflare.com CDN. The video is available here:
When using the “Preview AMP” button in “AMPforWP,” then “FV Flowplayer Video Player” seems to work fine.
Se screenshot A attached
When publishing the page, then the error message is as shown below:
Se screenshot B attached.
Please see the screenshot C attached.
“FV Flowplayer Video Player” works great on non-amp sites.