Hi Kaj,

Please do not use this review page as a support forum!

You rated 2 stars for not automatically activating it. However, you can customize the Turn Off the Lights Firefox extension, and yes you have the option to set the dimmer automatically when to a certain time or play button click. And more:
See this YouTube video tutorial:
How to automatically dim the web page at a certain time:
https://www.youtube.com/watch?v=bWYVktAvLeo

How to the Turn Off the Lights Options page:
https://www.youtube.com/watch?v=Sh4agktea9o

How to auto dim the web page when click on the video play button:
https://www.youtube.com/watch?v=U16evoySkac

If you need any help or have feedback, please do not hesitate to contact us at https://www.turnoffthelights.com/support
We are happy to help you over there.

Thanks,