Dumping the two videos with https://gpac.github.io/mp4box.js/test/filereader.html shows VIDEOv1 uses `mp4a.6b` for audio and VIDEOv2 uses `mp4a.69`. We just recently [added support for 0x69 to the parser](https://github.com/mozilla/mp4parse-rust/pull/276/files), but that hasn't been merged into Firefox yet. My guess is that change will fix this when it lands.
Bug 1693977 Comment 5 Edit History
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Dumping the two videos with https://gpac.github.io/mp4box.js/test/filereader.html shows VIDEOv1 uses `mp4a.6b` for audio and VIDEOv2 uses `mp4a.69`. We just recently [added support for 0x69 to the parser](https://github.com/mozilla/mp4parse-rust/pull/276/files), but that hasn't been merged into Firefox yet. I've confirmed with local testing that change will fix this when it lands.