(AFAIK they're ONLY available in Japan at the moment.)
https://forum.finalfantasyxv.com/discussion/1382/bonus-bd-discs-with-ffxv-film-collection-japanese-release-from-aniplexQuote:Among these extras are two bonus BD discs titled:
FFXV UNIVERSE ～BONUS DISC～ (Staff interviews and other)
KINGSGLAIVE ～BONUS DISC～(The making of KINGSGLAIVE FFXV)http://www.jp.square-enix.com/kingsglaive/sp/products/product03.html
https://www.aniplexplus.com/itemDVZUoGnj
https://www.amazon.co.jp/dp/B01DKGAR1M
[BDMV][Film Collections Box FINAL FANTASY XV][FFXV UNIVERSE ～BONUS DISC～]
[BDMV][Film Collections Box FINAL FANTASY XV][KINGSGLAIVE ～BONUS DISC～]
These guys are Bonus Discs #1 and #2 respectively, please kindly download Main Discs #1 and #2 as linked below:
http://www.nyaa.se/?page=view&tid=856263
http://www.nyaa.se/?page=view&tid=856365
