Yeah, the GOT show is based upon the books. Until the show passed the books, whatever was in there was mostly taken from the books, so I agree that the Vikings guy really doesn't have a good argument.
Any book readers (and writers) here might also want to check out my post: https://steemit.com/writing/@theinsideout/narrative-styles-explaining-g-r-r-martin-s-shifting-third-person-pov