When I turn left, at various speeds, I get a rubbing sound. It doesn't happen all the time. It happens a lot, but it doesn't happen each time I turn the wheel, but I'd say 75% of the time. Could it be something mechanical, or is something just stuck under there? I haven't had a chance to get under the car yet. I'll also try to take a video.

 

It also happened when I was driving straight, but I think the road was slanted down to the left.

Here are two videos.

http://youtu.be/PbaVhjAMXX8

http://youtu.be/ZcZIh_MiJAU

 

Worn brake pads if I had to guess. Mine made the same exact noise when turning left. Then after a while happened when going straight too. My pads were toasted when I ordered my brake parts and two weeks later they were delivered to me but it did get quite a bit worse in my case.

 

When was the last time you had an alignment done? My car was out of alignment even though it wasn't pulling in either direction.

Also, it could be a wheel bearing. If your pads and alignment are good, I'd recommend pushing on the wheels while they're in the air to feel for any play.

 

Wheel bearing noise increases as the speed of the wheel increases. The sound is exactly what my 08 sounded like a few weeks ago. What intake and or exhaust do you have on your car? Sounds pretty sweet.

 

Judging by the frequency of the squeal, it's likely your brake pads are getting too thin. Could be the wheel bearing but those tend to make a lower frequency noise and increases with wheel speed and when the bearing is loaded like when turning. See the following picture of a front brake pad:



Note that chrome piece sticking out the top? That's the inside brake pad. What you don't see is the face of the pad that touches the brake rotor. That chrome piece bends back onto itself and ends up at a certain depth of the pad material. When the pad material wears down to that point, the chrome metal end touches the rotor surface and makes a squealing noise to tell you that you've left the pad change too long. It's called an audible brake pad wear indicator. It starts to make that noise when you turn left because the inside pad on the right brake gets thrown to the right and makes the wear indicator contact the rotor. Pretty soon, it'll make the noise all the time, especially when you use the brakes.
At the very least, check the pad thickness to confirm. You can take the wheel off and look down the slot in the brake caliper to see both pads. You'll still have some thickness left because the indicator is designed to warn you long before it's dangerous. Change both front brakes at the same time. Also check the rears.