Firefox - Error H5P Interactive video: "Unable to decode media."

Hello all,

I am facing a strange problem with the H5P plugin for Moodle, specifically the "Interactive Video".
I have embedded some video into a course via this content type (as .mp4).

Via Edge (version 112.0.1722.58 (Official Build) (64-bit) (my default browser), the videos play flawlessly embedded in our learning platform.
But now I get the user message that after clicking on a video tile in the video player, the following error message appears when calling it via Firefox:

"Unable to decode media."

I was able to reconstruct the error in Firefox (version 102.10.0esr) (64-bit). The console gives the following messages:

"This page uses the non standard property "zoom". Consider using calc() in the relevant property values, or using "transform" along with "transform-origin: 0 0"."

"Starting Moodle session timeout warning."

"Media resource [video URL removed for copyright reasons] could not be decoded."

"Media resource [video URL removed for copyright reasons] could not be decoded, error: Error Code: NS_ERROR_DOM_MEDIA_FATAL_ERR (0x806e0005)
Details: auto __cdecl mozilla::SupportChecker::AddMediaFormatChecker(const mozilla::TrackInfo &):sadiganonymous class)::operator()(void) const: Decoder may not have the capability to handle the requested video format with YUV444 chroma subsampling."


Oddly, two of the overall 8 videos also play perfectly in Firefox, even though all of them were produced (or rendered) and embedded identically.

Obviously, it's important that video content works across all popular browsers, not just Edge.

Is there already a known workaround or solution for this?


Many greetings

Jonas