What's more to receive the file, now everyone who wants it has to download and process the entire block chain, a process that already takes forever just for financial data.
They only have to process the block chain from the point where people started including files in it, at block 123571, if you count my encoded bitcoin.jpg as the first such instance.
The reason processing the block chain takes forever is the signature verifications on the transactions. Skimming blocks of depth greater than or equal to 123571 to decode files would be blindingly fast.
Even generating arrays of all the inputs and outputs in the entire block chain, and checking that the unspent outputs total 50 times the number of blocks only takes a few seconds, if you employ flat files.
Reading 150 meg on a modern PC is a very fast operation.
The current bitcoin client gets bogged down on three things. Verifying signatures on transactions. Slogging through random access database files. And gratuitous beating on the IRC channel.
