Podcasts in Rhythmbox: removing special characters from the downloaded files

When Rhythmbox downloads podcasts, it uses the URL as a filename. I like to copy/paste the podcasts to my mp3 player with Nautilus. Unfortunately, my mp3 player has trouble with special characters like colons and question marks (':' and '?'). This is probably due to the FAT32 file system.

I use the following script (triggered from a launcher) to remove those chars from my podcasts:

#!/bin/bash
find $HOME/Desktop/downloads/ | while read f
do
  REN="$(echo "$f" | tr ":" "_" | cut -d '?' -f 1)"
  echo "mv $f $REN"
  mv "$f" "$REN"
done

After that, copy/paste of my podcasts goes fine.