What happens when you withdraw money to a vendor on nucleus via the page with the list that says: withdraw, deposit, etc (sorry, don't have the window open).
I've sent nearly $30 to a user; once for tip, the other for express delivery (since he didn't have the option).
If you withdraw to a vendors account irregularly then they get the cash, if you do it regularly they get banned for breaking the markets T&Cs and scamming the site