Can DirecTV/Tivo combo boxes record from cable, antenna, or other non-DirecTV source?
No. They only have tuners for DirecTV and have no MPEG encoders (they don’t need them since the DirecTV signal is already digital) so can not record from any source except DirecTV. Their RF (non-satellite) input can only pass an RF signal to the output when the box is in standby mode. The exception to this is the HD DirecTiVo which can record from antenna as well as DirecTV. Its my understanding that a DirecTV subscription must be maintained to have the program guide data needed to record over the antenna.