A suggestion for a Perl screencast: using the Perl debugger. ~1.5 years ago my friend found a bug in the Perl debugger that had rendered it basically non-functional for several releases. I think it's telling that no one picked up on that for so long (i.e. no one is using the Perl debugger, probably because they don't know it exists and/or how to use it).
[ IIRC, it might be the bug under: http://perldoc.perl.org/perl5100delta.html ; search for 'PERLIO_DEBUG' ]