Youtube videos display no picture when playing, but only sound on Firefox

[rraceanu]

Environment

OS: Win 10 Home 64 bit, build 10586
Firefox 46.0.1
ABP 2.7.3
Filterlists: Easylist Germany+ Easylist (default)

How to reproduce

1. Access www.youtube.com and disable ABP on youtube domain.
2. Access ​https://www.youtube.com/watch?v=kOkQ4T5WO9E with firefox (or any other video that has a pre-roll video ad)
3. During the pre-roll ad, pause the video ad
4. Enable ABP on youtube domain and refresh the page
5. Access ​https://www.youtube.com/watch?v=7tlZ876Fw90 (or any other video with pre-roll video ads, 10% repro)

Observed Behaviour

Youtube video is playing but no picture, only audio (Black screen)

Expected behaviour

Youtube video displays picture and audio when playing.

Other Information

When the issue was reproduced on Win 7 - 32 bit, Firefox 46.0.1 with ABP 2.7.3 I've received the following error:

TypeError: a[c] is undefined
​https://s.ytimg.com/yts/jsbin/player-en_US-vflVo2R8O/base.js
Line 1786

No errors encountered on Win 10.

Related discussions

​https://adblockplus.org/forum/viewtopic.php?f=1&t=45200

[rhana@getadblock.com]

Here's the post I made on the ABP for Chrome forum, reposting here at mapx's suggestion. Please note, we are seeing these reports from Chrome users.

Hi, Rhana from AdBlock here. We've had a rash of reports over the past several months that YouTube videos show a black screen but the audio plays normally. I spent a few days researching this, and all the solutions I found are in our KB article:

​https://help.getadblock.com/solution/articles/6000137829-youtube-videos-show-a-black-screen-but-i-hear-the-audio

The one common thread through all the reports I've seen (either reported to us or found on other forums) is that this only happens when either AdBlock or ABP is running. Pausing AdBlock or ABP and refreshing the page gets the video to play normally. None of us at AdBlock have been able to reproduce this issue. Links users have sent us as examples where this always happens play fine when we try them. Please note, we started getting these reports well before we migrated to ABP's core, yet both AdBlock and ABP have been repeatedly identified as the cause.

One of our users did some pretty extensive troubleshooting recently. He found that while the problem happens consistently with both AdBlock and ABP, it does not happen with uBlock. Here's what he reported to us:

---

Black screen with audio is being caused by adblock (tested)

As I mentioned briefly, the black screen bug is being caused by adblock. I have tested this multiple times through youtube and after removing the extension and replacing it with another adblock(not this adblock or the plus) it seems to be working fine. However when I tested your adblock once more after I disabled the one that seems to be working fine, I have come to a conclusion that this adblock is the cause of the black screen bug. Also this is happening with my other computers that contain this adblock. Most solutions is to disable hardware acceleration to prevent this bug, but the problem is that it causes videos to become more choppy and is needed when using a 4k monitor. The problem also seems to be recent as when I updated chrome which was around July 6th, it started to happen a lot. Strangely enough the bug seems to be more frequent at night around 12 am eastern.

Also i would like to note that I did test disabling hardware acceleration, but it only lessened the issue with the cost of choppy videos. Not only that, chrome and adblock is up to date.

The adblock that I installed that ceases this issue is uBlock. I did test both adblocks [AdBlock and ABP] at the same video but unfortunately [only] uBlock was successful in negating the issue.

Here is the video that had the issue: ​https://www.youtube.com/watch?v=zwCUqKdZ9xA

---

Brent has been looking into this on our side, but not being able to reproduce the issue is blocking further progress. We're hoping that if ABP isn't already investigating as well, putting more minds on this can only help!

Thanks so much!

[trev]

Mass-closing all bugs in Adblock Plus for Firefox module, the codebase of Adblock Plus 3.0 belongs into Platform and User-Interface modules. Old bugs are unlikely to still apply.