Prompt for password instead of requiring it as a command-line argument.  This way, it is neither displayed while you type it nor added to your shell history.  The only argument you should now pass on the command line is <your-itunesconnect-login>.
Prefix the file names with "NNN - " where NNN is the session number.  To avoid copy-paste errors I created a variable ${dest_path} which contains the path each file will have when a download is successful.
Edited the README to reflect that you no longer enter your password on the command line.  Also added comments about disk space (52GB for all the SD files) and how to get the HD versions (6x larger).
Merge pull request #1 from aglee/master

Prompt for password. Prepend session number to file name.