Video\Audio converters

MAC and Windows
any-video-converter
for windows and mac users. this video converter is recommended by Mr. Wood

For Windows Only
SUPER (C)
This is a very good video/audio converter. Download link is at bottom of the page

LINUX Only
This will require some command line stuff (it's not that hard)

First you will need to install ffmpeg
Go to Applications>>Accessories>>Terminal
in the terminal type:

sudo apt-get install ffmpeg

note: every thing is case sensitive

next we need to install a graphical user interface
in the terminal type:

sudo add-apt-repository ppa:paul-climbing/ppa

now type:

sudo apt-get update

type this and you're done:

sudo apt-get install winff

Optional: if you extra functionality type this:

sudo apt-get install libavcodec-extra-52

now in Applications>>Sound and video
there should be a program called Winff, thats the converter