Could it be that the rear axle up just need retorqued?..

 

I'm thinking that the axle nut is a little loose causing the rotor to tap against the rotor cover, I'm going to take the wheel off and see if it is loose(once I find an auto store to get a breaker bar, as the car has a locking lug nut set..

 

Ok update.
So I took the wheel off and tightened the axle nut.. Wasn't really loose but was able to give it a small turn.

It turns out that the rotor looks bent..
As in when I look at the rotor from straight on from the top one side looks further out than the other. Either the rotor is bent a little or the wheel bearing/hub is. Will update more in a bit.

 

It does sound a bit like something rubbing the rotor cover or splash guard (whatever it's called.)
From the video, it looks like the noise occurs more than once per revolution, so it's not a nail in tire. (Although, it could be more than 1... Sound isn't right, though.)
A warped rotor is the correct term for what you're exploring now. More common on the front than rear, but not impossible. I think they aren't that brutal to take off for better inspection. With that much noise, I doubt it can be ground down still within spec to fix it, but rotors aren't that expensive.
Try your drive with the e-brake on/off at different intensities to see how or if that affects the noise.

 

Dude! I use to get this fuhking noise all the time at low RPM's!
Seattle got hit BAD by a snowstorm in like November / December and this noise from my wheels started happening.
The noise has been coming and going for a while now.
I never figured out what the hell was wrong. Forgive me for my poor care of my Z.
But the past few weeks it has been gone, but in exchange, now my ride feels "bumpy"
I live on the bottom of a steep hill and when i'm coasting down the hill at around 10 mph, my head bobs back and forth because my brake is grabbing and pulling. I don't know how to describe my brake.
I'm going to assume my rotors are warped.
When braking, my pedal isn't perfectly smooth. I feel that it's slightly moving up and down along the warped grooves of the rotor.

I just wanted to let you know that this is probably going to happen to you.
Take it to a local shop that does a free brake inspection if you're on a budget. See what they say.

 

This is NOT typical rear axle clicking. Still it could be axle related.

 

Sometimes rotor warp is obvious. You can see it spinning the rotor. Other times it must be checked with a run-out gage.

 

Exactly what I was thinking...

Edit: watched vid and it sounds like something rubbing the sheetmetal shield behind the rotor.

 

So... Did your wheels fall off and the police have yet to find your charred corpse at the bottom of the cliff??
We want answers! It's impolite to leave someone half way through an HJ.

 

Sorry. Still not fixed. Rotors ordered but Havnt gotten them yet.
Not dead yet.. ; )

 

Ok, so problem is finally solved!!!! Man it's so nice to not hear the click/clanking noise!! haha

So I popped off the rotor and what do I find? This!


So aparently maybe the previous owner tried to take off with the parking or E brake up and it just dislodged the whole parking brake assembly. A couple parts are mangled lol. So I'm ordering a new parking brake shoe, and a hardware kit. For now I just took the one side off.

Anyhow the shoe had been rubbing up against the rotor, but surprisingly no damage to the rotor. Which I'm still replacing with some slotted rotors, as the front ones are junk.(you can see the grooves in the front rotors from 5+ feet away!!!!)

So thanks to everyone who had suggestions.. Sorry it took me so long, but I've been crazy busy with work and school. Any questions just ask

 

Weird! Glad you figured it out.
So, is that the parking brake's shoe contacting the bolt circle of the hub? (I haven't taken one of these apart yet.)

 

Glad you found the problem! That thing looks pretty mangled up..