Ah, just found a calculator, and it suggests that 60 minutes is CBR at DVD standard bitrate - was thinking that as DVD media always says 120 minute, that it implied maximum bitrate, but actually, VBR average about half.
Oh well, learn something every day - but then, with the 2 hour DVD5 being standard, that's probably almost as good as it gets.
Actually, as it's a program that a friend is going to be in (and they want a recording), probably best possible quality would be a TS stream capture and convert without recoding - not sure if the DVD/HDD recorder re-encodes or remixes (it DOES have an encoder, as it can also do analog tuner & inputs).
So maybe if I can get a TS recording with my PC DVB-T, and convert with
MPEG Streamclip can also convert MPEG-2 transport streams into muxed MPEG-2 files, for immediate burning at full quality with most DVD authoring applications