It was inevitable. With The Order: 1886 already in the hands of quite a few gamers, the first hour of gameplay has been published on Youtube.
Included is also a spoiler-free gallery of screen captures, for those that don't care for spoilers and prefer not to watch the videos.
Of course be very aware of spoilers if you do watch the videos.
The videos have been taken down, as expected, but the posts has download links for them all, so you can just download them and watch at your leisure if you don't mind spoilers.
Update 2: the video is now available again as a single long video. It's in the post, as long as it'll last.