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I can understand that you require your user to logging in and out of their account during video verification, but to show their google and binance account? I have to say I am not comfortable with "KYC" that deep.
Asking users to log into their personal & exchange accounts other than the concerned website has nothing to do with KYC.
I hope you can explain more, and perhaps answer what DaveF asked, it'll be helpful for me to write a neutral feedback to warn other [future] users of this... depth of KYC they might have to undergo, and their option, whether they'll get refund or are allowed to withdraw if they refuses to do so.
Unless someone complain that they are not able to withdraw the funds without verifying if a KYC request arises from them, this below quote from Rollbit is more than enough.
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We always refund users who are unable to complete verification steps.
There does not exist a single case where this is any different.