When you want to convert a video into audio just double click on the video file and at the bottom of it you will get a encode this option, no special software is needed.
If you select it you will get all these options. From the drop down list select audio only.
First mac will convert the video into apples specific audio files.
You can use these audio files with your iPad, iPod or iPhones. But if you want you can also convert them into mp3 files using iTunes.
The best part of this features is you can do this with multiple files at once. So batch processing works.