Perfect for my use case. Most other ultrawide video addons don't have an option for 18:9 and this has that and more.

This works very well for 21:9 monitors. Thank you.

Doesn't work at all.

I don't even have an ultrawide, but I use this add-on because letterboxed 21:9 in theater mode is super annoying
Edit: Makes YT pretty laggy. Not immediately, but over time

Used to be good, been using it for more than 1,5 year but recently it has become so laggy it's unusable, gotta remove it then everything turns to normal. 1 star

playing it with 4k is laggy. I try it with both Firefox and Google Chorme, Firebox is slightly better but still laggy. I use RTX 3070I for GPU and i7 10700K CPU. 32GB RAM. Its not using much of my CPU (30%-40%), memory (35%-45%) and GPU (40%-60%) but somehow it doesn't play smooth when I turn Ultrawidify on

It does all the work pretty well. Must have for 21:9

This plugin did not restore its default values on uninstall. I tried to use plugin to fix some wrong aspect ratio video but did not work as expect, so I uninstall but everything did not restore to its default.

migliore delle altre, ancora non perfetta, ma è l'unica adattabile a diversi player.
se ci fosse anche un pan&scan manuale, o magari anche solo uno step dopo il 21:9 (24:9, che potrebbe essere una buona visualizzazione per i filmati già 21:9 sui 32:9) sarebbe già da 5 stelle.

I'm using Windows 10 1909 on a laptop using Firefox nightly 86 64bit. And version
4.5.1.2 work only in theater mode on youtube but in full screen mode it leaves a big thick black on the bottom of the video.

Work greatly with desktop firefox. Please support android firefox.

This is amazing, even when a video switches back and forth it keeps up! This makes YouTube on an ultra-wide a vastly better experience!

Hey Tamius!! Hopefully I can get your attention! This is a great add-on. It's so close to being perfect for me. In my use case there are some videos that switch between aspect ratios within the video itself, could there be an option to just detect the first few seconds, or just the initial aspect ratio and then not change it after? That way it's not distracting when the video constantly changes back and forth every few seconds of play time. Here is an example video in my use case for test with your add-on: "https://youtu.be/uT15kycq-3I" (3:38-4:05 is a good example )If you can't add this to the base add-on then what would I have to change in the advanced options code to achieve the behaviour that I would want. Thanks, and I appreciate what you've given us ultrawide users!

So far, so good. Automatic video detection works and saves the hassle to manually switch modes. Needs better UI, but otherwise 5 stars.
Relevant specs: 34" LG WK650 and RX480

Really great addon, thank you :-)

Super extension, extrêmement personnalisable.