Help, '06 engine making rattling noise

My '06 Prius just started making this noise.

the check engine light is NOT on. I haven't really heard this noise before in my recollection. I just got an oil change 3 days ago and when I got the oil change there was no indication from the dealership that there were any issues. The engine only makes this noise when the combustion engine is engaged. I can't see any wobbling on the belt drives or and loose parts in the engine. The spin appears to be coming from the engine block or around the pullys for the belt. Does anyone have any ideas or clues. My first thought is tht it could be dirty gas because I first heard this sound after filling up. I appreciate any insight. I am 300 miles from home and have to drive home today.