It worked with FF 56 and after I upgraded to Firefox 61.0.2 - 32 bit it stopped working on over half of stored links (torrenting, anime online, kisscartoon ...) On some it shows only a blank window on others it does not show even the icon (hon3yhd.com, torrenting, rarbg..) as if it's not there. On 1337x it switches from preview into full screen and you actually end up on the page you wanted to preview... and so on
Hope you can fix that someday.

I really like to have an replacement for Cool Preview, but current version 1.00 is way to slow to be useful.
I hope future versions will fix this.