they take loans out on make up as far as I know and pay a mark up on it, so they might borrow £1000 and add £1500 to the make up
so they are playing on a wage basically
Not strictly how it works Iron, basically if you're staking me and you give me a £1000 loan on make-up then you'd add £2000 to our make-up figure because in order for me to have physically made £1000 for myself (which is what i've received here) then I'd need to have won £2000. So if our make-up is £0, you lend me £1000 and I win £2000 the next day then you'd get the £1000 you'd have won anyway, plus the £1000 that you loaned me.
If our MU was at £0 and you lent me £1000 and only put £1000 on then I went on to win £2000 then I'd get £500 and you'd get £1500 effectively knocking yourself for £500.
The other, fairly significant thing to remember about borrowing money on MU is that technically speaking if you were to then drop me the money you'd loaned would be dropped as well - although often, depending on the circumstances of the dropping decent people will pay back the money that was "loans" as part of the MU (or at least commit to on there next score etc)
So basically it's an interest free loan from the backer, but secured against future earnings (as secure as that can be in poker)