Rewatching the video, and I picked up a couple of other interesting points of note that was not covered in the Q&A about materia:
- Materia will no longer be dependent on gear slot. Hence, it will now be possible to attach to all types of materia to all types of equipment.
- In accordance to the above change, each item will have a 'cap' to how much of a certain stat it can increase dependent on the item's level, thereby making mix-and-match more important.