"Criticize ideas, not people." The etiquette applies to everyone I believe.
To clarify: the "idea" is to improve developer productivity by replacing an outdated tool with present day solutions. That topic wasn't discussed, only me.
As I'm the only engineer working on MediaViewer and I'm doing so for free, I find this treatment very disrespectful. Such treatment is an obvious contributor to the developer decline (T160508).

Thank you, Tgr! I found out how to trigger and test the functionality. When the "wiggle" appears is reasonable, I have no plan to change or improve it. I'm not sure I would interpret the wiggle as it's supposed to be, but I've noticed the extendable metadata panel without the wiggle, anyway.

In T243920#6603986, @Aklapper wrote:

@Demian: Why has this suddenly become high priority?

Using a mixin duplicates the rules at each use site. With 9 rules that creates unnecessary bloat. A normal CSS class is better for this purpose, wordpress has .screen-reader-text, that's fairly widely understood and common.
However to address Volker's disapproval of a single utility class the rule can be made with an attribute selector as done in this commit:
<span screen-reader-text> Audible, but not visible text </span>, that's similar to and consistent with the CSS standard
<span hidden> Content not displayed </span>

Thank you, @SubodhKulkarni. Following the above steps I can see subtitles. We need to reproduce the problem you're experiencing to be able to investigate it. For this we'll need more information. Can you provide some of the following (the more the better)?

1. What is the resolution of your phone?
2. What operating system and browser your phone has? What is the version of these?
3. Which player do you see? The one with black background or the other one with white?
4. Which language did you select? I assume English?
5. A video recording of your actions - if possible - would be very helpful.
6. Please open the second video (https://w.wiki/GSk), choose English, play the video to exactly the -5:00 time as seen in the screenshot below, pause it and take a screenshot if possible, with the subtitles menu open.
   

These project names 😆 They don't make it easy to report a bug...
Same element ID used on desktop and mobile (emulator):
https://gerrit.wikimedia.org/g/mediawiki/extensions/TimedMediaHandler/+/b74ee2ab2778e74b4b3217b33e5a89d79ec8bb01/includes/TimedMediaTransformOutput.php#55

@Tgr thank you for your insight! I'll look into maintainership, though I don't expect that would avoid consensus. Does it?

The deadline for this task is the first 1.36-beta release.

Courtesy ping: @Krinkle @daniel @DannyS712 @Nikerabbit

All merged it seems to me.

@Aklapper this discussion is about unilaterally declining a task with a clearly false reason. Can you please discuss that without making accusations and correct it?

In T247010#6597122, @Aklapper wrote:

No, please see my previous comments. Throwing millions of links at people [...]

As I've said read my comment detailing the "misunderstanding": https://gerrit.wikimedia.org/r/c/mediawiki/extensions/MultimediaViewer/+/574636/41#message-6bc135e88a5cda27f27045871676ecdbf0216c21
The comment you've referred to is factually wrong. I've explained the facts, if those are not understood then I can't help further.
Please make sure that this discussion continues collaboratively and professionally, without edit-warring on a Decline flag.

In T266977#6598120, @Aklapper wrote:

Reflecting discussion in Gerrit that this should not be done.

The parent task has no discussion about this. Task still needed and open.

Moved patch to T245838

Moved patch to T245838

In T257087#6597215, @Aklapper wrote:

there should not be open stray tasks around, so I resolved it.

I wholly agree with that, however this is not a stray task. Otherwise I wouldn't mind ;-)

Thanks for the clarification. Yes, that's an annoyance, but seemingly not bad enough to spend time fixing it.

Thanks for the help, @Tgr. Reproduced it.

Hmmm. I've overlooked this:

"only for those people that have not opened the metadata panel before. "

In T266983#6595399, @Tgr wrote:

See T77463: Animate metadata panel when opening Media Viewer for what that code does.

In T257087#6594783, @Aklapper wrote:

In T257087#6594464, @Demian wrote:

@Aklapper is there a need to close this?

@Demian: See T257087#6278367.

In T247010#6594786, @Aklapper wrote:

No, see T247010#6445613

Yes, I remember. However that approach failed with mediawiki-discourse which remained largely unknown throughout the developer community, presumably also due to a lack of explorability. I think this time a more proactive approach should be taken, or we'll see history repeat itself.

Demo for MonoBook Echo patch: http://demian-demo.epizy.com/?useskin=monobook

@Tgr do you remember this? What's your opinion?

@Aklapper Would it be possible to add the following links to the notification on https://discourse-mediawiki.wmflabs.org/ ?

* [Wikimedia Chat (Mattermost)](https://chat.wmcloud.org/)
* [MediaWiki unofficial (Discord)](https://discord.gg/ZrV2Ex9)
* [Outreachy chat (Zulip)](https://wikimedia.zulipchat.com/) 
* [Hackathon chat (Telegram)](https://t.me/wmhack)

@Esanders The clean solution in the long term is to move .oo-ui-toolbar up 2 levels in the DOM into .mw-content-container (which has the right dimensions), just above main#content.mw-body and completely remove the margin rule.
This however only works for the new Vector yet, all old skins, including Timeless need some custom margin-left in that spot. Nevertheless that's technical debt and should be eliminated for future skins.

After a long wait the patch has been cleaned up, rebased and updated for a final review.

The submitted patch resolves this bug too.

The submitted patch resolves this bug too.

The submitted patch resolves this bug too.

2020-11-02: I can't observe a FUOC. There's black background until the image loads, which is AFAIKT as intended.
@Esanders is this issue still present or could you close this task to reduce the outstanding tickets in backlog?

This was resolved by Simon's patch. Tested in Chrome Version 86.0.4240.111.

Thank you @Samwilson and @Shirayuki.

Aaaand... it's gone. Thank you, @DannyS712!

Last change to svgmin settings was on 2018-11-29: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/MultimediaViewer/+/476440

2020-11-01: I've run svgmin (svgo 1.3.2), no changes.

Nope, I did not claim the task. Ed submitted the patch.