The Amazon copy finally arrived. Turns out it's a Zone A version, however it appears to work in both my Zone B BDPs:
- Sony BDP-S380 (sat in a black screen for a while [maybe it was trying to do BD Live], but I skipped to the menu and it played)
- Panasonic DMP-BDT320 (played 100% normal)
What's more, this Zone A disk has the HD audio and special features (which are NTSC which is sub-optimal, but I can still play them on the PC without stutter).
What's going on with the zone thing though... My BDPs aren't modified. Why can I play Zone A disks on my Zone B hardware?