They seem to be using https://www.eternum.io to "pin" the file (keep a copy of the file alive). Since eternum is a paid service they might unpin after a while but it's up to them. If they didn't do that, the file might only be available as long as your browser is open.
In this case the file is served by a javascript implementation of ipfs running inside the browser over websockets. I'm not sure if the server is pinning the files as well.
