Works perfectly, using it to stretch youtube videos to 16:9 in fullscreen (no cropping), because some videos have black bars on the left and right sides when in fullscreen, but Ultrawidify fixes that automatically, all you have to do is go into settings and select 16:9 stretch hybrid.

PLS BRING THIS TO OPERA GX, we need it sooooo bad

Fixed my twitch and youtube, saved my marriage, cured my stomach ache and drove my kids to lacrosse practice every day. Not a single add on does that, but if you believe in yourself and in Tamius, it is possible. Dont let your memes be dreams!

Works well. Ironically, I'm using it to stretch 4:3 to widescreen so it looks correct on my crt (adapter shenanigans)

I constantly watch web streaming, whether they are of individuals or movies. With the help of this add-on, the black bar issue was resolved. I'd want to thank the developer.

Great addon, but only for technophile users. Again and again the addon has to be readjusted on different levels. Usually, the addon works without major readjustments across all major streaming services. Sometimes, often with DisneyPlus or PrimeVideo, I have to readjust certain settings via "Site Settings" (Enable/Persist) and "Advanced Setting" (Limit Zoom) so that I can restore a 21:9 image via VideoSettings. After a lot of trial and error with the settings at the beginning, I can now almost always change the picture to 21:9 without any loss. Knowing this, the addon is indispensable for 21:9 fans. Thanks to the developer!

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.

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

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!

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