Brett built his own PC and he's trying to move files from his old Mac. But his Passbook external drive doesn't see all of the files from his Mac. Leo says that's because Mac and PC use different file formats. Macs can read PC files, but Windows can't read Mac's HFS+ file system. So to be cross platform, he'll need to format the hard drive to FAT32.
Luiz has a hard drive that Windows can't read and it wants to reformat it. Leo says chances are that it was formatted with Apple's file system, rather than Windows file system. Leo recommends copying the files off of it using a Mac and then reformat the hard drive to FAT. Then copy it back. The Windows machine will be able to read it then.
Another option is to just buy a second hard drive that is already preformatted in FAT and then just copy them over from the other hard drive with the Mac. Then he'll have two copies, one being a backup. It'll then be a simple drag and drop.
Apple has announced major changes to their OS X file system. Replacing HFS+, the new system is called APFS and has some nice features that will include being more reliable. You'll be able to unplug a hard drive and the file system will be more robust and not crash the system. Another advanced feature will be Snapshots. It'll basically be an automatic image copy done in the background so that you will be able to get back up and running in a few minutes.
Apple has also announced SWIFT Playgrounds, which will enable kids to learn how to create apps on the iPad.