In the simulator sometimes you need to use the Debug -> Trigger iCloud Sync menu to trigger the sync. It is not automatic like on iOS devices.
If you keep having issues then try these sample apps which include code for handling iCloud account switches, moving from local to iCloud, making backups, storing and fetching backup files in iCloud, etc...
BTW that wwdc2012 session is old so I would look at the more recent wwdc2013 session 207 video for things that have changed in iOS7, OSX 10.9