Hmm, well it says nothing about verification for BTC withdrawals so what would be "big" withdrawals? 200 BTC or more?
I don't know, but their terms of service say that at any time they can suddenly demand verification. They say they are always monitoring for suspicious transactions, and I suppose any giant Bitcoin withdrawal would get flagged. However with the volume going through the exchange they would probably consider 10 BTC small change.
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