Well, it's revealing parts of the DLC that people who haven't played it yet might not want to see. That's pretty much a spoiler. Not a plot spoiler, granted, but a spoiler nonetheless.
If you mean the
, then that's just a location that doesn't spoil anything. It's like if someone completed the game's main questline, made a video showing to go to the Throat of the World for the Notched Pickaxe, and then that was considered a spoiler because of the location, even though no context was given as to its place in the game's plot or when it is reached. I deliberately tried to keep this video spoiler free.
Spoiler'd the location in case that was the issue.