Work so perfectly.

PROS:
Very productive and stable.
This screen capture add-on (FireShot) let me modify the file name before and set the saving folder path before, then the file name will auto generate and the saving is very fast.

CONS:
(1) if you type screenshot or screen capture or printscreen on the Firefox add-on search box, it cannot show this add-on. You must type screen shot or print screen to search this add-on. I prefer all of the "screen shot" and "screenshot" and "screen capture" and "print screen" and "printscreen" are acceptable to search this(FireShot) add-on at the Firefox add-ons searching box.

(2) There are 2 web stores limitation.
If I want to capture the entire webpages screens at the Firefox add-ons pages(here), I need to use Chrome with this extension.
If I want to capture the entire webpages screens at Chrome web store, I need to use Firefox with this add-on.