i don't see the difference between story spoilers and gameplayspoilers streams, gifs, etc...
We all know the game contains cars, shooting, running around, locations, etc. People want to see the particulars of what those look like. These are not "spoilers" except for the extreme people who put themselves on complete blackout. Those people are obviously not clicking on this thread if they're serious about those kinds of "spoilers."
The story is the story. It happens once, then you know it, and that's it. You don't ever get to experience it fresh again. Some people don't care about that, and that's fine, but it is clearly different from watching someone free-roaming.
I hope you see the difference now.
In any case, unless the thread title explicitly said "ENDING SPOILERS INSIDE" I would not expect untagged major plot spoilers for an unreleased game on NeoGAF, ever.