I have installed the W2G extension in firefox as well as kiwi browser but it does not seem to open the pop up for custom video playback AKA W2G Sync.
How about instead of opening a dedicated window it opened a pop-up window, maybe then it might work on the mobile device.
Because after we use a custom URL for playback it informs us that this site is in no way related and other stuff and below that there will be an open button.
You are right the mobile support for the extension is quite weak. Most mobile browsers do not support extensions at all, Firefox is an exception… The next time I work on the extension I will spend some more time testing on FF mobile. Maybe there is a way to get it properly working.
Thanks a lot for considering it and for making W2G 
Firefox support extension on Mobile, while Kiwi Browser supports Chrome extensions on Mobile, just a quick tip…
Thanks a lot for that input. I haven’t had Kiwi browser on the radar yet!