Question about sound coming from left front while braking

I just bought a 2007 Prius, with only 120K for $5000 dollars. I was pretty happy with the deal even though I heard a strange sound coming from the front left area while test driving. I asked the car dealer about it, and he claimed to be the world's experts on Prii, and ensured me it was absolutely nothing. Obviously I'd like to get a second opinion. I notice this sound when I press the breaks, or when maybe sometimes when the electric engine is engaged. Oddly enough, I also sometimes hear the same sound when I parked the car and leave it.

I've tried to make a recording of the sound by placing my phone on the hood, close to the source of the sound, press the power button and pump the breaks.

I'm thinking about getting a check up of the car in the near future.

 

Thank you identifying the issue! I have the feeling the sound has actually gotten less frequent since I got the car, so I'm pretty confident it's nothing to worry about. You made my day!