hard to say from the video, but it could be lifter noise. I have lifter noise with my 93, it happens mostly on a cold engine, and happens every so often, not all the time. I just ignore it. As a matter of fact, it hasent happened in a few weeks...... anyways.
What weight oil u running? mileage on engine? can u hear if its from one side or the other of the engine? center of engine?
if it is lifters, Id pull valve covers and inspect which one(s) it is, but im an ASE certified tech, this is second nature to me. If its a rod knocking.... thats a whole other story....