Before my engine completely failed, it made a noise very similar to what I hear in the video. The sound would come and go randomly. In fact the night before the engine finally failed, it sounded perfect, but then the very next day the sound was worse than ever and did not go away.
The problem was caused by bearing failure. One of the bearings between the crankshaft and connecting rods would spin in place and block off the flow of oil to that point, causing the noise, then it would spin again and allow oil to flow properly.
Each time it did that it caused more damage.