Record multiple channels from one multiplex
From MythTV Official Wiki
This feature refers to a feature of DVB which can have multiple channels for each frequency transmitted. That means one tuner can record from more than one channel at once, where they share a multiplex. In the UK, where multiplexes can carry ten or more channels, it would be incredibly useful.
This currently can't be done.
Handle multiple DVB channels simultaneously from a single multiplex. Also have a look at this Ticket: http://svn.mythtv.org/trac/ticket/1772