It doesn't sound "clackity" enough to be the decompression device. At least on the few times my G5 had the auto-decompression thing stick on very cold mornings it went clack, clack, clack, at half engine speed. It also quit if I revved the engine up just a little and once it was gone, it didn't return.
I hear a number of different sounds and I'm sure the mike is being moved around to different places.
I hear the tickity tickity of the valves, the thump thump of the exhaust and occassionally a hollow thunking sound that sounds like piston slap. I think I read the bike had been ridden before these recordings were made so the piston should have expanded making the piston slap guess unlikely.
Because there are so many different tappity, clickity, thumpity's going on, it sounds like a case for the Hose-ear.
I know you old timers already know this but, if one takes a short length of garden hose and holds one end to their ear, they can move the other end around to various strategic places to get a better definition of where the noise is coming from.
Sounds from the rocker arm areas would be valve clearance, sounds from the cylinder (front and back) might be a loose piston, clunking sounds from lower down on the crankcase may be bad bearings, whirring sounds from the crankcase are roller or ball bearings...etc....etc