So, I am not a mechanic but that video sound might be timing chain whip. Definitely it is not injector nailing noise.

How's the timing chain and how many miles on it? Although often when the timing chain is beginning to get loose, you can hear a metallic jingle. Cheap insurance to replace the timing chain at 200K miles.

You should check the timing chain guides also for broken pieces etc.

Sorry it get complicated.

Good luck!!

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD