Chronotube v1.3.0
This is a tiny addon that evolved from my userscript.
It simply updates your URL when you're watching a YouTube or a Twitch video so that it always contains a timecode at the position you're watching the video.
This makes it a bit simpler to share videos with timecodes, but the main reason is to store the position at which you stopped watching the video in the browser history.
You may look into addon preferences for the offset - by default it is -1 so the timecode lags behind the actual video for one second, it can be any number - even positive if that is needed for whatever reason. Also the preferences allow you to specify the timecode format - there are two interchangeable formats supported by both YouTube and Twitch at the moment.
Addon icon was made by Freepik from www.flaticon.com