They wouldn't have commentated for bits that the BBC weren't showing. It wasn't unknown for them to re-record commentary for later, non-live showings like for Monza 1990 (giving Murray a chance to positively identify Warwick's Lotus when he had his big scary crash (that he walked away from)).
A good example would be the 1981 Monaco Grand Prix, where the BBC had only just gone back to the race when Piquet crashed. That's why Murray's commentary says, "You've joined us at a tremendously dramatic moment."
I know they sometimes added commentary on for the highlights but I assumed that was just generally to tidy stuff up for the jumps. I remember I think it was at Argentina 1996 when Murray got Hakkinen and Coulthard mixed up for a bit, but in the highlights he got it right at the start but then reverted to getting it wrong again after they went back to the original commentary.
I might be wrong then but I always thought they commentated right through (in case stuff went in the highlights and because they'd be watching anyway so they might as well keep their vocal cords warmed up!), but could still refer to the BBC audience joining them in the live commentary but just not use it in the highlights. And also it could potentially mean a lot of after race work for the commentators if they missed out a lot of interesting stuff live.
Some races were only ever shown as highlights and often you can tell if commentary is genuinely live so I might try and test this out.
But also didn't other countries use the BBC commentary as well, and they would have had more live showings?
Edited by PlatenGlass, 30 March 2020 - 17:10.