I would have thought the bits you noticed were the divers own set up? You buy the DSMB and instead of attaching a reel you attach .................
I have seen a diver off one of the UK boats do similar. He attached a 10(ish) mtr line to his DSMB with a lead fishing weight on the end (folded up very compactly). When he got to 9 mtrs he opened the DSMB, dropped the line and inflated his DSMB and let the line run up through his hand as theDSMB ascended.
Personally, I prefer to know the bag is on the surface before I leave the wreck as we can have strong tides running after the slack and I like to know the skipper can follow me as I drift off the wreck. Sending the line up from 40 or 30 mtrs requires a decent sized reel (IMO). I just clip the reel and bag to the cylinder D ring on my twin set before getting in and I never notice it is there. I've never got it caught up on anything yet.
DIR divers prefer to use a spool but what a pain in the arse to wind the line in again.
If need be, I reckon I could winch myself to the surface with my reel and DSMB.