DownThemAll (or just dTa) is a powerful yet easy-to-use Mozilla Firefox extension that adds new advanced download capabilities to your browser.
DownThemAll lets you download all the links or images contained in a webpage and much more: you can refine your downloads by fully customizable criteria to get only what you really want.
DownThemAll is all you can desire from a download manager: it features an advanced accelerator that increases speed up to 400%, it allows you to pause and resume downloads at any time and, last but not least, it’s fully integrated into your favorite browser!

Install this extension,just click install in this page and restart your firefox.

Right click on firefox page,and there will be the two options:

downthemall

Click here for more details