Bugzilla

yeah, it's possible that we're getting different content, due to A/B testing or something on the server side,
and what you're seeing is actually GIF animation.

I confirmed that it's video element for me.
when the autoplay starts, I see the following element in the page, which is playing the pixelated video.
(you can search it from inspector https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/index.html , search with ""jw-video jw-reset")
when I call `pause()` on it (secondary click on the element in Inspector, select "Use in Console", and enter `temp0.pause()`), the video stops,
and when I call `play()`, it starts playing.

```
<video class="jw-video jw-reset" tabindex="-1" disableremoteplayback="" webkit-playsinline="" playsinline="" src="blob:https://www.imdb.com/fadd85d6-89d0-435e-beb2-085bce8f10b7"></video>
```

can you check if you get the same thing?

Also, given that you get different behavior between regular installation vs portable, it might be caused by something in your profile.
Can you check if you get the same behavior with temporarily created clean profile, with the comment #6's steps?
(don't forget to set "Block Audio and Video" setting)
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

yeah, it's possible that we're getting different content, due to A/B testing or something on the server side,
and what you're seeing might actually be GIF animation.

I confirmed that it's video element for me.
when the autoplay starts, I see the following element in the page, which is playing the pixelated video.
(you can search it from inspector https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/index.html , search with ""jw-video jw-reset")
when I call `pause()` on it (secondary click on the element in Inspector, select "Use in Console", and enter `temp0.pause()`), the video stops,
and when I call `play()`, it starts playing.

```
<video class="jw-video jw-reset" tabindex="-1" disableremoteplayback="" webkit-playsinline="" playsinline="" src="blob:https://www.imdb.com/fadd85d6-89d0-435e-beb2-085bce8f10b7"></video>
```

can you check if you get the same thing?

Also, given that you get different behavior between regular installation vs portable, it might be caused by something in your profile.
Can you check if you get the same behavior with temporarily created clean profile, with the comment #6's steps?
(don't forget to set "Block Audio and Video" setting)
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles