For some reason, I have a bunch of recorded tv programs in the database but the video files cannot be found.

How can I remove the missing programs from the database?

Is there a way to totally clear the table of recorded programs and then run myth.rebulddatabase.pl to populate the table from scratch?

You really don't want to do that. At the very least it's a lot of tedious error prone work and it's not necessary.

To fix this manually:
- Find the names of the files listed in the DB that no longer exist on disk.
- Touch the files into existence.
- Delete as normal.

Someone also recently posted a set of DB utility scripts, including one that fixes this problem. You want the 3rd one down: http://knoppmyth.net/phpBB2/viewtopic.php?t=17454

The 3rd one did the trick.

The problem is that Comcrap encrypted a bunch of channels so my HDHR couldn't record them.