I am the one who filmed those videos.
That siren has been running like that for years. Not sure what is wrong with it, but I suspect it's something with the phase converter. It can't be capacitors, since this siren is not single phase. The motor is probably going bad as well. Not quite enough to send it to the graveyard, but close.
I used to post about it a lot and was obsessing, so I have cut down on my posts about it.
My mom lives 6 miles away. On a clear day/night, we can hear the Allertor.
If you think it sounds sick, check out this one. This one really is dying:
https://m.youtube.com/watch?v=zWBVvaZ9S7I