expert ....please show me this code, for easy read. thank a lot.

[toml...@gmail.com]

hi,
i',m the newbie in perl and i get the follow code.
it is the script for download youtube video .
i would like to know that"how to retrieve the %3a to : and %2f to / in
this script
and read this script more easy.
any one can help me, i want to get some from this regpex
"file name getyoutube.pl"
"/getyoutube.pl http://www.youtube.com/watch?v=kH8cS1AkqiI"
#!/usr/bin/perl -w
use LWP::Simple;LWP::Simple::get(shift) =~ /<title>YouTube -
(.*?)<\/title>.*player2.swf\?(video_id=([0-9a-z]+).+?)\"/is && exec
"wget -c -S -O $3.flv \"http://youtube.com/get_video.php?$2\" && ffmpeg
-i $3.flv -ab 56 -ar 22050 -b 500 -s 320x240
\"".(@ARGV?shift:"$1.mpg")."\" && echo && echo YouTube:$3 saved as
\\\"$1.mpg\\\""

in case, about the ffmpeg and wget, i understood what that doing,but
in perl(rexp) i can't understand.
may be the flow...i also no 100% understand,can expand ?

thank a lot.