CoolPreviews no longer supported. https://www.coolpreviews.com/

https://addons.mozilla.org/En-US/firefox/addon/coolpreviews/ AMO says: "This add-on has been removed by its author."

Acquired by Yahoo at the end of 2014. https://www.cooliris.com/ I guess that you'll need to check with Yahoo as to the future or that add-on.

Spiritual_2 said

I was using Cool Previews before your last upgrade but after it was not available, pity because I found this ad-on very useful. Thank you for helping me, Michael.

Hi, I was also using the add-on Cool Previews until yesterday when I was prompted to update to Firefox 37.0.1 ... I also found it extremely USEFUL and now seem to be having difficulty without it! Somebody PLEASE fix this or create an equal add-on!!! Thanks.