I like this add-on! I use it for multiple Google and YouTube accounts and it works well! That's so convenient! Good integration e.g. it can open tabs in a container from the top sites page and from the Firefox - File menu. It would be nice to have an option to access the Containers' menu via right clicking on an opened tab (for accounts to be switched automatically if it's technically possible). Or even via page context menu. Also hotkeys would be very handy for some users. Anyway, many thanks to the developers for this very useful add-on.