They will be using Storj. It is in demo mode,
https://k.im . They stated he has chosen Storj.
Just to put this into perspective, if you do actually try out the k.im demo, you can see a whole list of services to choose from, besides Storj also Siacoin, IPFS and Filecoin are listed for example, and the big established services like Google drive, Dropbox, Box.net etc. What was shown are early demos, not a finished product, you don´t even actually upload any files to the listed services yet in that demo anyway (I have tested this), so I would be cautions and not jump to conclusions, and wait to see which of all the services will be really available in the actual working product in the end.