You can get MP3 from YouTube video file by converting YouTube FLV to MP3 with MP3 Converter for Mac software.

1. YouTube to MP3 for Mac Converter, Convert YouTube to MP3 for Mac OS
YouTube to MP3 for Mac Converter is a good assistant for Mac OS users to extract the MP3
audio track from downloaded YouTube FLV files. Once conversion completed, you can put the
MP3 on your iPod, iPhone, iPad, PSP, Zune, Sansa, Creative Zen, Walkman, etc. Besides MP3,
you can also convert YouTube to other audio formats, including WAV, M4A, WMA, AAC, AC3,
RA, MKA, etc.
Simplified guide: How to convert YouTube to MP3 for Mac OS?
Before converting YouTube to MP3, you need to download and install the MP3 Converter for
Mac.
Step 1: Locate YouTube file
Add your favourite YouTube file to the MP3 Converter by clicking "Add File" button.

3. Step 2: Set YouTube to MP3
From Profile list, select MP3 format, then click "Browse" button to set output folder to store MP3
file.
Tip: You can set the audio encoder, bit rate, sample rate, channels by click Setting to set
parameters directly.
Step 3: Convert YouTube to MP3
Now, click "Convert" button to start converting YouTube to MP3 on Mac. The process bar will
show you the conversion process.
You'll get MP3 from YouTube video within a few seconds!