I had to google "scubido" but I used to dive.... a long time ago, as a young man. Tried it again about a year back and suddenly found it very claustrophobic.
Every oring in the regulators and BC were lubed with silicon grease- again just enough to say that it's there, but not so much you have a big ole blob of it on the oring- right before reassembly and it was so natural to do that it was unthinkable for me to reassemble the valve block without doing it... but these guys on here were so adamant, I was beginning to wonder if there's some new kind of self lubricating viton that they're using nowadays.
@sjp873 the fact that so many people on this forum- experienced guys at that- haven't had any problems without greasing the orings probably illustrates how rare problems are even if you fail to do so.... but they CAN arise. All it takes is an oring that deformed a little- maybe shipped unsupported in an envelope, maybe packed less than flat- and which keeps that little deformity through the first pressurisation because it wasn't lubed enough to slip into place, or an oring that probably moved a little as you reassembled whatever you were working on... and you'll have a leak.
@Bertie Wooster had an infuriating time recently when a newly rebuilt valve block kept leaking all the air out of the left rear airsrpring and he had to disassemble it to find a twisted oring on the plunger stem.
It's stuff like this that you want to avoid. 99 times out of a 100 you'll probably be fine as the experience of our members shows.... but that 1 time you're not.... you'll spend maybe a whole week chasing your tail trying to get your rebuilt block to behave properly.
I dunno about vaseline though.... I get leery at the thought of petroleum products in contact with rubber so I've never used it. It's always been silicon spray to clean the surfaces the oring comes into contact with, and a light smear of silicon grease on the oring itself- right before reassembly.
Good luck!