Hey, Colin - I'm guessing that the unit looks like the one on the ebay link that you initially posted, maybe? Maybe they changed the pic on the listing for a newer model after you got yours?
https://www.ebay.co.uk/itm/303094925953?ul_noapp=true
The one pictured certainly has the mic and reset bits on the top left, as opposed to your unit which in your video has them on the right. And it has no sd card slot on the front, or anywhere else I can see on the manual pages at the bottom of the ebay listing. Which is not the end of the world, I guess, but you'd be limited to the 16gigs of internal memory. Shame, though.
But on the bright side, it's still a lot more storage than the Highline Mk3, even including the CD.
Kwil, good luck with the installation. I'd love to hear how you got on as I'm seriously considering going the same route.