My car just started making this noise when I apply the brakes. It persists for a few seconds after but only if the car is moving.
Any ideas what is wrong?
Edit: this might be the problem?
It sounds as though your brake pads have worn down to the metal
Brake pads are considered a consumable in the car industry, much like oil or tires.
Brake pads have material that is bound to a metal backing plate. When that material is used up the metal backing plate can begin to grind on the disc or rotor.
Once the metal to metal contact begins a groove is worn into the rotor.
If I am correct with the sound you have worn out the brake pads and are digging into your rotor with the backing plate of the pad and are rapidly destroying the rotor. If you get past the pad in wear you will begin to wear out the pistons in your caliper.
I suggest you replace your rotors and pads quickly if this is the case.
You can remove a front wheel and look at the pad against the rotor to confirm this theory.
best of luck.