It just works.

Forces 21:9, absolutely terrible

It works well but there are alternatives such as UltraWideo that do this better. My biggest gripe is: it plays normal 16:9 videos stretched *or* zoomed to your full width so that you miss half the screen. And since there's no settings or shortcut to turn this off, this sadly doesn't work for all "normal" 16:9 videos.

Work perfectly!

Works on YouTuber perfectly on my Moto G7 Power!! Will report if other platforms (Netflix, Hulu/Xfinity StreamPix, etc-etc) DOESN'T work correctly. 👌👍

work perfectly

first one that didn't just zoom in the video and cut off half of the video I was watching. This one worked perfectly.

I see LuffySDP seems to have edited his comment to point out that your add-on doesn't work anymore.

To repeat what he already said, it doesn't work on the current version of Firefox and the 2 last ones.
I myself am also an addict of your add-on and truthfully, I can't live without it anymore either.
So, I would like to express you my gratitude with a BIG THANK YOU and I eagerly wait for your fix.

By the way, since you didn't answer LuffySDP, I guess you didn't get any notfication for the edit of his comment, so can you maybe give us a way to contact you (mail) in case such issue reappears again ? Well, if you don't want, I'd also understand.

Thank you once again for this incredible add-on and please, fix the issue quickly. Bye

If I only had to have 2 extensions (since an adBlocker is and will always stay first), it will be this one.
I watch a lot of videos, especially animes and for around 1 or 2 years, I rewatch the old animes that didn't fit my screen and always had this annoying black borders.

The consequence was that I was forced to download the animes to watch them on VLC where I could change the ratio. But I lost time to download them and I couldn't even keep them because of a lack of space on the disk.

So for me, this extension is really a blessing.
The best point of this addon being that you don't need to interact with it as it will automatically detect the format of the video and adapt it to your screen. For now, there hasn't been a single error of dimensions (for example the video exceeding the screensize or so) and it really is the perfect solution.
Well, by reading the comments below I discovered that we can use the X and Z buttons to interact with the video but I really don't think you will ever need it.

I'm actually quite sorry to only post a comment more than one year after I started to use it, but I didn't it was possible. I only discovered it a week ago when there was a problem with a firefox update and I had to switch to downgrade firefox to v63 and looked for a way to contact you ( even if utlimately I didn't post since someone did it before me). Anyway, thanks for the patch.

I really recommend this extension to everyone and once again, a BIG THANK YOU to the developper of this addon.

EDIT : I DON'T KNOW IF YOU GET NOTIFICATIONS ON COMMENTS EDIT, BUT NONETHELESS I'LL TRY.
I DON'T KNOW WHY, BUT YOUR ADD-ON DOESN'T WORK ANYMORE. I TRIED IT ON FIREFOX 63.0.3 / 64.0 / 64.0.2 BUT IT JUST DOESN'T WORK.
PLEASE, CAN YOU TRY TO FIX IT ? IT MAKES AROUND 2 OR 3 WEEKS I CAN'T USE IT ANYMORE AND IT'S A TRUE TORTURE FOR ME. I ALREADY CAN'T LIVE WITHOUT IT ANYMORE. PLEASE !!!!

I use it since a couple of Firefox's updates but now doesn't work with new Firefox v.64. I downgraded to v.63 and still works. Waiting for an update to work with new firefox.

After last update firefox 64 the Ultrawidey do not working automaticaly on youtube! , also Z key not working, but X key is working , but i have to press X evrytime??. I downgrade to Firefox 63.0.3, now automaticaly work and Z key working to on youtube . Can u tell me why?
Thanks for your update 23 dec 2018, great job, now it work on firefox 64 thanks

Nice extension which does what is needed. However, it does interfere with Google Calendar. It is no longer possible to switch between Day/Month/Year View.

it works really well !!

works well on youtube!

nice..working for me!....good job!

Not working with steamstore website. First video is streched like intended, additional videos on the store site remain untouched.
Nice easy control. Would prefer some kind of edge/blackborder detection for interchanging content (some content like modern trailer show the preview in 21:9 with blackbars but the cinema announcment in 16:9 inside same video).
Also website profiles would be nice.

Seems to work great from everything I have tested. Also the options are minimal, which I honestly like.

Something to note: Yes, it stretches the video, but I would rather have it stretched than black bars. It does well at exactly what it is suppose to. Great addon!