It's an official stream agreed between Asianboxing (who basically nagged) and CBC (the broadcaster). It's run through the CBC youtube with Asianboxing having a license to host it (apparently contracts and shizz had to be signed)
No one has the rights because there's about 5 different channels showing the sport in Japan. It's not like the UFC
You have CBC (who are showing this, and are affiliated with TBS), TBS (who have Watanabe and Ioka signed up) NTV (who have links to Teiken, but haven't shown much this year), G+ (who are an NTV affiliate), Fuji (who do Inoue, Murata, Ken Shiro), then you have things like Boxingraise (subscription service from Dangan/reason), a-sign (which put their fights on youtube on delay)
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