There are several slides (#14, 17, 36) in the presentation that refer to "ZFS version". This is incorrect, those are the "Zpool version".
Both the ZFS and the Zpool have a version number. They are not the same, and are not interchangeable.
Most systems are ZFS version 5.
To see both numbers on your own system, you can run the following commands:
# zfs upgrade -v
# zpool upgrade -v
Note, if the above commands are run with "-a" option, they actually perform an upgrade. This cannot be undone! There is no back-out if you change your mind! But without the "-a" they don't change the system and are safe to run.