Need advice on this engine

[SeeNi]

So I have a 2000 318i and was planning to buy a 320i that I found on facebook marketplace for 500$. The reason it's that cheap is that it is a foreign car that cannot be registered in my country at all and left front end is slightly crashed (dented bumper and broken headlight) so I wanted it for the interior, some suspension parts and the m52b20 engine but I called the seller today and he said that engine has 185000 km (115k miles) and is working fine along with the gearbox but the cat and headers are missing so I asked him if he could send me a video of engine running because he is not very close to me so that i wouldn't have to travel 2+ hours for an engine that will not start. He sent me a video and my dad said that he can hear the knock in the engine and that it's not worth buying so I wanted to ask you guys on here if you can hear anything wierd from the video that i posted here. (sorry for crap english)

https://streamable.com/aujb4p

[E39 Newbie]

It's hard to tell over the exhaust noise, but to me it sounds like valve train noise. It will be interesting to read others' opinions. The mileage is pretty low for an engine of that year. It's probably sat a lot and been neglected. For $500 I'd buy the car, put some Liqui-Moly engine flush though it, and some decent oil, and see if the sound gets better. The interior and suspension bits are probably worth the $500. If the engine is any good then it's a bonus. If it's not, you can probably earn back a few dollars by selling the rotating assembly and head.