It doesn't say it was from the market place, it says it was found on an on-line forum. I think it was a scam hoping people would want NetFlix on their Android phone when it wasn't supported yet. There have been a number of modified netflix apps doing the rounds but all have to be downloaded and installed without the market place. If you download and install stuff that you don't know the author and it's not from the market place then you take your chances and you have to accept the outcome, whatever that might be.
That's not to say that this hasn't happened through the market place in the past because it has, there was a bunch of dodgy apps on there not so long ago