The link you posted might be a malicious link since what you are talking is too good to be truth.
The internet is not so good for morons. Maybe you should try TV? Any link might be malicious. You just gotta take the risk some time. But, I'll tell you this much, what I am talking about is true. Amazing eh? Just click on a few of those addresses and blockchain.info immediately tells you if you hit one with a BILLION FUCKING DOLLARS on it. You can capture that money TODAY. No lie. This is real. 100%.
You can thank me later.
then everyone could check if his private key was publicly known 
Trust me, it is 100% that your private key is publicly known and is in this database.