Hello Graeme,
These people who've been telling you otherwise, are they by any chance would-be Archie hunters who just can't get over getting their ***es whupped?
I wasn't aware that there was any disupte about Kubodera and Mori's photographs (it wasn't a true video). There's been some animated discussion about the fact that the squid lost a tentacle in the encounter, and about what the photos may reveal about Archie's general demeanour, i.e. active hunter vs. pasive feeder, but there's no disputing that it was Architeuthis.
I hope that you will bring all of this to the attention of your ill-informed peers, and make them cry.
Cheers,
Clem