I use Video Download Helper and DownThemAll plug-ins for Firefox...
Basically gives you a list of downloadable objects from the website you are on and yeah..

I use this for videos too and I just so happen to have Sony Vegas Pro so I cut the video and render it as MP3....

DownThemAll is a download manager that lets you paste the URL of the link that you would get from Video Download Helper, which is the tool that lets you pick what you want from the website you are viewing.

I'm sure you can figure out how to use it...........
Or you might not even need it by now.........
But there are tutorials online