Affected versions*

• 68.0.1, 69.0b9, 70.0a1(2019-07-29);

Affected platforms

• macOS 10.13

Steps to reproduce

1. Launch Firefox and set layers.acceleration.disabled to true;
2. Restart the browser;
3. Access any video on youtube;

Expected result

• video plays without issues;

Actual result

• video controlers and some frames flicker baddly

Regression range

• manual downloads and double checks for multiple videos could only get so far as the results bellow;

• First bad: 2018-08-12-22-06-18-mozilla-central/
  https://hg.mozilla.org/mozilla-central/rev/d999fb858fb2c007c5be4af72bce419c63c69b8e

• Last good: 2018-08-10-10-01-28-mozilla-central
  https://hg.mozilla.org/mozilla-central/rev/83d0673bbca49e9713f5326708cf9908f2d71764

Additional notes

• attached recording with the issue;
• on most cases the issue was triggered instantly but on some it appeared on the 2nd or 3rd video;
• case on a macBook Pro - Intel Iris plus graphics 650.

Ryan, do you think your patches could have impacted this?

It's certainly possible. Could you flip the 'layers.omtp.enabled' pref to 'false' and see if it still reproduces?

Yes, it still reproduces.

The issue is still reproducible on latest Nightly 73.0a1 (2019-12-09) (Build id: 20191209215019) using Mac OS 10.14 and 10.15.

Encountered this too, on this demo on 74.0b2, macOS 10.15.

Issue still manifests with 78.0b2, 79.0a1 (2020-06-02) .