Although it's masked under the general tappet and engine noise I'd say it's the cam gear starting to go. Listen to mine. It was already terminal then. I drove it happily down to my garage to have it changed (another YT video shows pictures) knocking like that. The previous day I had driven it back from the Southern BKV at Fort Nelson back to Kent! Cruised at 60 fairly quietly.
https://www.youtube.com/watch?v=iXxSRQ0johk
If you were using one of those mechanics stethoscopes you might find a wooden broomstick from the timing cover and pressed into your ear works better. Beware the fan!