Hello Don,
First of all, be careful when measuring the oil level on your KV6. It should be done with the engine at normal operating temperature and
after waiting five minutes for the oil to drain down into the sump. Here's
the official MG Rover procedure to be followed.
I've listened to your video. It's significant that the noise subsides a few seconds after a cold start. I've had this on two occasions to varying degrees. I'd say that you might have a belt tensioner on the way out. The fact that the engine cut out is worrying and you say that you "limped" home. Was that because the engine's performance was severely reduced or were you just driving very carefully?
Simon