Hi,
did you mean this video:
Porsche Boxster Noise IMS Bearing? - YouTube
Sounds like a hydraulic lifter problem to me. Also the fan is very loud. If it's a harder knocking it also could be a big end bearing problem (piston rod).
But as i said, a failed IMS will lead to bad engine timing because the chain is jumped over or to a total loss because the chain is torn. I don't think you can hear a bad bearing - and that won't be Tac Tac Tac, because it has to be a grinding, or abrazing noise when a ball bearing fails.
An oil check is a good idea. If you like to do an oil change you can also inspekt the filter. There are also laboratories that can examine oil samples.
Regards
Markus
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