Thank you for making this small but quite effective extension! I used to use YouTube High Definition extension but it stopped working a while ago and not in a continuous maintenance anymore. Before finding this extension, I have tried a dozen of other ones to get a wide screen view in the window mode, but ended with nothing practically useful: they either used JS/CSS tricks (which resulted in a still big blank space at the side with overlapped recommendation sidebar), or required paid subscription for overkill functions. However, this extension just made things work again: a native wide screen in the window mode without interfering with other YouTube components on screen. Great experience!

Doesnt work when exiting fullscreen...It does what you say...too bad default cant be theatre mode after exiting full screen...This is called youtube ruining youtube.

doesn't work. 1 in 3 videos or so still are in small windows even after manually forcing the theather

Fantastic extension. It does what it says, and it does it natively, which means theater mode just happens--no weird resizing glitches to wait for. The app uses the minimal amount of permissions possible. Well done.

work as intended. it just works. thank you so much

It doesn't always work.

my fovorite addon, but no work now(2022/10/22) . please fix it！

Love it, but it no longer works! Please update.

Could you please provide an update so that the add-on works with Firefox Multi-Account Containers.
I asked for help on r/firefox and a gentleman provided the solution in this thread.

https://www.reddit.com/r/firefox/comments/x6bqb3/addons_to_force_youtube_to_always_play_video_in/

YouTube must have this as toggle setting!

Expand View does not expand to fill the viewport, at least when the browser is full screen. And full page view overflows the viewport.

Also, when clicking on video search results within the YouTube site, it always takes me to a posting by zFrank instead of the selected video.

It does what it says it'll do but there seems to be some kind of error. With this add-on enabled, putting anything into the Google search bar takes me to whatever I was searching for's website instead of the Google results page. I've disabled this add-on and tried a search again and things went back to normal. So it's this add-on that causes the Google search to do this. Please fix