Find iTunes songs with specific format (MPEG 1, Layer 2)
If the files have mp3 as the extension, mdfind kMDItemContentType==public.mp2 or searching for kind:mp2 in Finder won't work either.

You could try using mplayer's command line utility. It can be installed with Homebrew or other package managers.

IFS=$'\n'; for f in $(find ~/Music -name *.mp3); do mplayer -identify -frames 0 "$f" 2&gt; /dev/null | grep -q 'layer-2 audio' &amp;&amp; echo mv "$f" ~/Desktop/; done