In the following video people discuss the best prints for the adv campaign (min 4:21)
Do they eventually scan the color prints (instead of the negatives) and use them for the job?
Prints look glossy so I wonder how they scan them.
No reason why not scanning from the original, you want for reproduction purposes to be as close to the version out of the camera. It is also possible & was often done from a print.
The question is about the process being shown in the video. The photographer and possibly the art director are examining contact proofs, and later prints. I assume they are darkroom prints since there is a rotating darkroom door right there. They are choosing the prints to be used--probably scanned and retouching done to the digital files before being incorporated into the magazine.
That YouTube is from 2012 and apparently the original shoot was 2011.
While it is likely that the eventual ad campaign involved digital pre-press, it may instead have involved an analogue pre-press work-flow.
If so, there would most likely have been separation negatives prepared from the prints.
Even if it was digital, the scanning process would have involved scanners with considerably more quality than your Epson 800 series.
Keep in mind the V600 can use ICE on photo prints to eliminate, lessen, or correct damage like tears, wrinkles, creases, etc. It also color corrects faded photos.