Buying BTC from a forum member is stupidity, even if the member has high green rating of trust your money can corrupt the person into giving up his or her account, we have exchanges for buying and selling coins, they are lot safer
Exchanges require kyc. So that may not be a problem for you but it is for some of us. I would rather do it peer to peer like btc was designed.
Yes, the exchange requires KYC when you want to buy bitcoin with any virtual card. In this case, this forum is a solution of buying bitcoin without KYC. But you have to more aware during trading. using escrow services is highly recommended.
And yes, green trust it does not mean the user can not scam you. Basically when a lower rank account achieves some trust in very short periods. I also recommend you to trade a small amount always when you will not use escrow. also, keep aware about bitcoin double-spent. Don't send your money without any bitcoin confirmation done. Best of Luck