Kind of hard to tell from the sound on a video...
But sometimes a misfire/ jumping spark makes a ticking noise.
Possible those knuckleheads messed one of the wires during the tune-up.
You can visualize a misfire sometimes if you look at the area in pitch black dark.
Maybe since it has two plugs per cylinder, performance isn’t affected? I’d think it would throw a misfire cel though.
Could be something else

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97 e300d, 78 300Dt, 95 E300d, 94 E320 estate