Can you help identify the source of this kind of noise?

Just a guess, but check the front struts, and see if you can detect any oil escaping and leaking down the sides. Or it could be one of the rubber engine mounts has torn.

 

A control arm bushing is worn out.

 

How much loose junk do you have in the tire well? At that mileage a good front end going over is in order. You could take it to the dealer, but OUCH, it might hurt a bit. If you have a local independent Prius Mechanic in your area, that might be a less expensive option.
It does however sound like it won't get better by itself, so a fixin is in order!

 

Wow that car sounds awful. Something seriously amiss in the front suspension and would make me afraid to drive the car. I assume you not mechanically gifted to climb under there or you already would have so take it to any tire place asap there pretty good at diagnosing this issue as I bet its pretty obvious. Try to avoid the dealer as you will get a serious rumping there. Nothing special at all under there from a regular car.

As a comparison my 07 at 60K makes no noise going over bumps and does not do that weird moan on De-celeration either.

May I assume this is a used car to you? Was this a salvage car? What brand tires are on this car. If you reply Goodyear Integrity's I shun you.

 

The noise in the video is exactly the same as I had on my Prius (217,000). It was the front sway bar (stabilizer bar) "D" bushes that were worn. It's not an easy job to do as the front suspension cross member has to be removed or at least dropped at the rear to gain access to the bolts holding the brackets. Interestingly, the noise disappeared when the temperature dropped to near freezing and returned in the Spring when the ambient temperature became warmer.

 

Mine is making same noise and was the stabilizer bushings. $20 shippped from rock auto. Common issue on many different cars. Mine were worse when the weather got below 30-40 degrees.

 

Yeah stab links are a pain. I like Rock but don't be surprised if the stab link nuts come loose. The suspension stuff you buy at Rock is alot of Chinese crap like Moog and the thread metal is so crappy it won't hold a nut on.
Did you notice how poorly the nut threaded on the rod?

This has happened on a few cars for me. Once I called Rock and complained and they told me to throw the part in the garbage and they credited me. Didn't even want them back. That was cool. Learned my lessen buy the OEM. They cost alot more but there's a reason.

You may get lucky and be ok though. Good Luck.

 

On another note, when approaching a bump in the road try to brake before you hit the bump and then just coast over it, this will greatly extend the life of front end components. Same thing with RR tracks etc. brake before and just coast over them. Much easier on everything..