YouTube video displays black in H5P Interactive Video, but audio and interactions work

YouTube video displays black in H5P Interactive Video, but audio and interactions work

Since August 19, 2026, YouTube videos used in H5P Interactive Video on my Moodle site have stopped displaying the visual/video component.

The video area is completely black. However:

• YouTube audio plays normally.
• The H5P timeline works normally.
• H5P interactions appear and function normally.
• Seeking/play/pause work.
• The video duration is detected correctly.
• Vimeo videos used in H5P Interactive Video work normally.

These same H5P Interactive Video activities were working correctly previously.

Environment

• Moodle 4.5.2
• H5P Interactive Video versions installed: 1.26.35 and 1.27.9
• H5P.Video library: 1.6.66
• Moodle native H5P / Content Bank

Testing performed

I have reproduced the issue:

• In Chrome
• In Edge
• In Chrome Incognito
• On a separate mobile device using Chrome

I also created a completely new H5P Interactive Video using a YouTube video and get the same result.

I created a normal Moodle Page and embedded a YouTube video there. The YouTube video plays and displays normally.

Therefore the problem appears specific to YouTube playback through H5P rather than YouTube embedding generally on the Moodle site.

Using a Vimeo video as the source in H5P Interactive Video also works correctly.

Browser console error

When the affected H5P Interactive Video loads, the browser console reports:

Uncaught TypeError: Cannot set properties of undefined (setting 'style')

The error occurs in the YouTube player initialization path:

at create (...)
at window.onYouTubeIframeAPIReady (...)
at www-widgetapi.js:185:153
at www-widgetapi.js:185:203

DevTools identifies the failing H5P JavaScript statement as:

player.g.style = "position:absolute;top:0;left:0;width:100%;height:100%;";

At this point, player.g appears to be undefined.

The console also reports:

Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('https://www.youtube.com') does not match the recipient window's origin ('https://fluent1.com').

Summary

The problem appears to be specific to the interaction between H5P's video player and the YouTube IFrame API:

Normal YouTube embed in Moodle: works
Vimeo in H5P Interactive Video: works
YouTube in H5P Interactive Video: audio works, but video is black

Could this be a compatibility issue between H5P.Video 1.6.66 and a recent change in the YouTube IFrame Player API?

I would be happy to provide screenshots, console output, or perform additional diagnostic tests if useful.