First, you need to look at human attention as a commodity just like gold - available in fixed quantity and everyone wants piece of it. It turns out that FB managed to conquer large portion of human attention after it emerged. This also meant massive attention transfer from news media to FB. However until year ago, FB benevolently gave back significant pie of its attention share to news media by heavily promoting thei…
This is why Facebook had a huge push into video—they wanted a slice of that pie. They haven't made much headway there.