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.

El único que funciona siempre

perfect !!!!!!!

Does its job!

This is the best smart ultrawide extension you can get. Most other either you have to keep toggle on and off depends on the content aspect ratio. This one is automatically detect the content and fit the content to your screen ratio. WOW

it do not streaching the image automaticaly on youtube??, so you have to click evrey time on video stetting/ streaching/ basic??, when u run another videoclip you have to click again to work. Can u add the function to automaticaly streach image?? (on function ''site checking youtube'' i have ticked streach based but this fuction doest work but is doesnt work cause i have to click evrey time on video stetting/ streaching/ basic)

Great extension for Ultrawide(21:9) users.
The only problem I have is with the stretching mode
Even if I set in Extention Settings
Enable this extention: Always
Default stretching mode: Basic
I even set in Site Settings
Default stretching mode: Basic
I am watching full screen video in youtube and its not stretched so I need to exit full screen click Ultrawidify video settings and click on basic and only then enter full screen again and it stretched, so even though its experimental it works but exhausting since its not automatic and there is no keyboard shortcuts for stretch mode.

A must have extension for 21:9 users, it's not perfect, but better than anything else.

I tested a couple of ultrawide video extensions on the Firefox Add-ons site, and this one is clearly superior.
One feature I miss is an on/off toggle (by keypress), or an option to rebind the shortcut keys.

Does its job. Minor complaint: upscaling artifacts are quite noticeable, maybe give an option to play with various blur options?