I had previously recorded the Catalyst series on children's hospitals for my sister (she's a pediatrician) and needed some good way to get it to her. Most of the automated DVD burning scripts for mythtv assume you're recording in MPEG2 (either from a PVRx50 or DVB), I record to MPEG4. The roundabout solution is:
Use
nuvexport to export the recordings to DVD style MPEG2. This automatically detects that the recordings are PAL.
Create duplicate entries for these MPEG2 recordings in the database (I just copy the original and change the channel number)
Copy these mpeg files into the myth recordings directory as .nuv files with the requisite names.
Use
mythburn through the mythweb interface to create a DVD iso. This automatically creates menus and the like.
Delete the duplicate recordings in mythtv.
Burn the iso.