• [Affected versions]:
  Nightly 70.0a1
  Fx 68.0
  Fx 69.0b11

• [Affected platforms]:
  MacOS 10.12
  Windows 10x64
  Ubuntu 18.4

• [Steps to reproduce]:

1. Launch Firefox with block autoplay enabled
2. Go to https://www.youtube.com
3. Click to open any video in a new tab
4. Click on the autoplay crossover icon
5. Open the autoplay drop down options
6. Wait a second for the content blocking information to load
7. Observe the autoplay dropdown

• [Expected]:
  Autoplay drop downs should not shift when other site information is loaded

• [Actual Results]:
  Autoplay drop down is shifted if opened before the content blocking information is loaded

• [Note]: Issue is reproducible when autoplay dropdown is opened before the site content blocking is loaded

• Regression: Not a regression, issue seen on the old autoplay implemented in Fx 66

This is not applicable in Nightly anymore because the content blocking section got moved to a different panel and it's basically impossible to fix for any other release.