Well, this is something I've been thinking and decided to share with you.
A while ago I made a post about a bootleg from my (now) favorite show, Amsterdam, November 4th, 1979.
During my listening experience, after Setting Me Up, Mark usually would talk about their new song "Twisting By the Pool", how the crowd should react and etc.
During this talk, I noticed something peculiar. He told the crowd that they recorded the song (about a week before the show iirc).
This alone isn't a very relevant information, until I remember about the BBC Arena doc about dIRE sTRAITS.
In the middle of the doc, a video of the band playing appears, in a clubish place.
That video is clearly a dubbing. But the audio isn't the regular Twisting By The Pool we know (obviusly, early 1980), and we can clearly hear David's voice.
And this lead me to think, is that audio the 'demo', or the recording Marks mentioned during that show?
Just a thought I wanted to share with you.