Try Google Video!

This new Google product (currently in Beta testing) will allow you to search for content from recent television programs.

I did a search for "Dateline and DXM," looking for a Dateline program that I saw on the dangers of abusing over-the-counter drugs such as Robitussin and Coricidin-D. While it didn't pull up the program that I was looking for (a 2004 Dateline episode), it did retrieve a March 2005 episode that also mentioned DXM. I was then able to see screen shots of the program as well as closed-captioned program excerpts.

Google Video searches the text of closed-captioned transcripts to find search matches. To find out more about how it works, visit here.

What I saw as a problem: it does not index past coverage from highly relevant sources--such as the MSNBC page that features video from the exact broadcast that I was seeking.