Closed Bug 1740487 Opened 2 years ago Closed 1 year ago

Video does not play at with ETP set to STRICT


(Core :: Privacy: Anti-Tracking, defect, P3)

Firefox 96



Tracking Status
firefox96 --- affected


(Reporter: rbucata, Assigned: twisniewski)


(Blocks 1 open bug, )



(3 files)

Attached image Screenshot_8.png

Operating system: Android 11
Firefox version: Firefox Nightly 96.0a1 (2015844771 -🦎96.0a1-20211109093712🦎)

Private browsing mode
Clean profile

Steps to reproduce:

  1. Navigate to :
  2. Tap on the ""Play"" button inside the video placeholder
  3. Observe the result

Expected Behavior:
The video plays

Actual Behavior:
The video does not play


  • Not reproducible with ETP set to STANDARD
  • Works as expected using Chrome
  • Screenshot attached
Severity: -- → S3

It appears that our IMA shim is simply missing an isSkippable method on its Ad class stub. Defining it fixes this breakage.

Assignee: nobody → twisniewski

While the patch I'm landing soon seems to fix the problem on mobile, I'm not sure if it fully fixes the problem on desktop, so I'd like to leave this bug open until I have time to investigate further.

Keywords: leave-open
Pushed by
add Ad.isSkippable to the IMA SmartBlock shim; r=ksenia,webcompat-reviewers

On desktop there is indeed a little more to the story on this page. If a video is initially unable to autoplay, then an attempt to play a tracking ad before it will also fail, and IMA detects this failure and handles it differently from how our shim does right now. Basically, their code expects requestAds to send an error message in that case, and they will then try again when the user clicks on the video (and it should then work as the shim does now). With that the video also works on the desktop page, regardless of autoplay settings (from what I can tell).

In addition there is an extra console error triggered due to the page which can be prevented by delaying our Amazon apstag shim a little (the same solution as in bug 1764041, except that here it doesn't seem to actually break anything, just spam a console message).

Oh, and it's worth noting that the first time one visits this video's page (regardless of ETP settings) there is some kind of race condition which causes it to fail to be able to play the video at all. The user has to reload the page after accepting their cookie banner before things start working (at least that's how I'm experiencing it). It seems to be a case where they are calling their prebidder script before it has loaded.

At any rate, I have a patch almost ready to land to fix this.

Pushed by
have the SmartBlock IMA shim test for autoplay on calls to requestAds, and error appropriately if needed; r=ksenia,webcompat-reviewers

I've confirmed that this is now working on the latest nightly release on desktop.

Closed: 1 year ago
Keywords: leave-open
Resolution: --- → FIXED
Blocks: 1773100
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