Ipfs is awesome! I look at the hash like a compressed version of the file. when your ipfs node requests it, it asks peers if they have the full/uncompressed version. a peer would have the actual file if they either 1) pinned/saved it to their node, or 2) have it in their cache because they have viewed the file recently.
So IPFS makes files/data/communication impossible to alter, and extremely difficult to delete (impossible to delete as long as even one ipfs node has the data in their cache). The more popular a file is, the more people have it in their cache, the quicker it is do download/watch for any new person.
Also.. It is being developed so that filecoin (a cryptocurrency) will have value. Filecoin is a currency you would pay to make sure that a file on ipfs is 100% for sure backed up and available and could even pay more to have it hosted on a bunch of nodes so it is widely accessible by multiple people wanting it at once.
Very neat stuff. Will alter the internet/communication/IP rights enforcement significantly I believe.
RE: What Is IPFS?