mybitcoin.com merchat services questions

[lesh]

hi, I'm writing a bitcoin accepting service, I plan to handle all the payments myself, but for comparison, I've checked out a mybitcoin merchant services and their Payment Button. and its super fast. it detects payment a few seconds after it was sent. how is this possible? also, how can they protect themselves from double spending if they accept unconfirmed payments?

thanks

[Alex Beckenham]

also, how can they protect themselves from double spending if they accept unconfirmed payments?

They make up for it by refusing to refund over-payments.