Download Pazera Free Audio Extractor (see Resources). This program does not need to be installed. Instead just unzip the folder to a directory of your choice. Launch the program by double-clicking on "AudioExtractor.exe."
Click "Add files" and select the files you want to add then click "Open."
Choose the directory you want the MP3 file to be saved to. If you want to save it to the same directory as the original, check the box next to "Output Directory = Input Directory." If you want it saved to a different directory click the box below that and then go to "Browse." Select the directory you want and then click "OK."
Under "Audio Settings" choose "MP3 - MPEG-1 Layer 3 (LAME 3.98)."
Click "Convert" and an MP3 with the audio from the AVI file will be created in the directory you chose.
Download and install AoA Audio Extractor Basic (see Resources). This is the free version of the program; you do not need the advanced pay version. Launch the program after installation is complete.
Click "Add Files" and select the file you want to convert to MP3 and then click "Open."
Under "Output Options" click on "To MP3."
Select the directory you want the MP3 saved to by clicking on "Browse" under "Output Path." After choosing the directory you want click "OK."
Click the "Start" button and the audio from the AVI file will be converted to an MP3 and saved in the directory you chose.
Download and install Free Audio Convert Wizard (see Resources). Launch the program after installation is complete.
Click "Add" to add the AVI files you want to convert. After selecting the AVI files click "Open" then "Next."
Click on "Select" to choose the directory your converted file is saved to. Then under "Convert To" select "To MP3."
Click "Convert" and the audio from the AVI will be saved as an MP3 in the directory you chose.