You can find more information on the speaker's site:
Most users don't ever realize just how much of a memory hog Perl is. Being Perl, however, the language makes it easy to find out. Using Devel::Peel and Devel::Size. This talk uses both to peer into scalars, arrays, and hashes and shows some ways to reduce the overhead when dealing with long-lived or high-volume applications.
Viewers should walk away with enough understanding of the modules to track memory use in their own code.