I'm using the final RTM build of Windows 10 (10240) and the latest available Intel Graphics 4000 drivers with my Intel NUC (first installed version 3389, then used version 10.18.10.4226 - same problem w/ both).
I have two displays (Display 1 = 1080p TV; Display 2 = 1080p monitor). In both instances I've made sure in the intel graphics settings (and w/in windows settings) the displays are correctly set to 1080p / 60FPS.
When I set the display configuration to Duplicate/Clone mode, Display 1 (TV) will always yield horizontal tearing toward the top of the screen when watching videos or any other content (youtube, games, etc.); Display 2 seems fine. This indicates that the FPS output to Display 1 is not truly being set to 60FPS despite it being set as such in the settings. When I change the configuration to only Display 1 (not duplicate/clone mode), the tearing is gone. To confirm the issue is w/ the FPS and not some video rendered, I tested every renderer and 3 different video players (VLC, Windows Media Player, MPC-HC)... the problem exists for each player in every renderer. Furthermore, the tearing is more evident when I intentionally set the FPS to a lower than 60 value, as would be expected.
It appears there is a bug in the drivers for Windows 10 wherein duplicate/clone mode is not correctly sending 60fps to both displays (but only one). This issue was not present under the same system / drivers for Windows 7 previous to my upgrade. I have tried uninstalling-reinstalling the drivers to no avail.