Engine making a rattling/slight grinding

Engine making a rattling/slight grinding (Video)

Hi all,
I noticed this after a recent oil change. There's a rattling happening somewhere in my engine. Hard to tell but seems to be coming out of the engine itself, not the alternator. It almost sounds like a rough idling, like something knocking around, which led me to believe at first it might be low oil. I've heard the '04 year had the wrong oil capacity down so maybe they underfilled it? I checked the oil the other day (a few weeks after the oil change) and it was slightly low, so I added about 1/3 qt that I had on hand. Still hearing the noise though. I plan to check the oil again today and add more if it's low. (Side note, should I do this while it's cold, or run the engine for 5 mins, turn it off, then check?)

Has anyone experienced this and/or can identify this noise? (see video below)

Thank you!

https://youtu.be/LsVRajFfRgM

Edit: just checked the receipt again and it says they put 4.5qts in.