u/Dvllie

I noticed this sound last night while driving and it gradually went away, drove it this morning with no noise, but got in just now and this is what it sounded like when I sat in it for a minute with the engine running, it stopped after a minute. It had its MOT two weeks ago and they said it had two advisories, one being that I would probably need my exhaust fully replaced at some point, but I knew that anyway as my car was quite loud to begin with, and the other being an oil leak in the engine, he said it wasn’t major though. I was wondering if anyone could help me figure out what this is before I have to take it to the garage? Thank you!