Look, the guy asked you a legtimate question; how do u know its mtgox? i know how to read the block chain as well and there is nothing to indicate its mtgox who did that tx.
there are other addresses in the past that have accumulated over 400K BTC's as well if u click back thru this exact chain leading up to this tx.
The transaction shows where the money originally came from. I receive bitcoins at Address A. I send them to Mtgox. Mtgox sends them to singular address. Since I know what my address was, and the exact amount I transferred, I know it was mtgox doing the transfer because I can trace the btc back to myself.
thats fine and true. sounds like you're just conjecturing what davout is alluding to. i'd like to hear that fact from him, though, since he's the one pointing the finger at mtgox. but unless someone recognizes an address there's no way to tell from the block chain itself who sent what to whom.