Rear wheel squeaking. Halp!!

[Therefore]

The video says it all but it's louder when going in reverse than forward. There isn't a pulsing when I brake hard. Ideas?

Video:

http://www.youtube.com/watch?v=CRVGnKD_lvw&feature=youtube_gdata_player

Hd after work.

Sent from my iPhone4 using Tapatalk

[scratch]

Sounds like normal chain sounds, and you are going to hear them as being louder in reverse.  The bike doesn't normally run in reverse.

Is the chain lubed?

[adidasguy]

Could be chain going bad OR rear wheel not aligned properly and chain is hitting sides of sprocket as it goes onto the sprocket.
Remove chain guard and eyeball down the chain. There are other threads on aligning the rear wheel.
Also - what did you do just prior to hearing that sound? Change the wheel? Lube the chain?
As you rotate it, check the chain tension every 1/4 turn. Does it vary a lot? If so, then chain is binding and time for a new chain. Trey's did that after I lubed it. PO never lubed it so O rings were dry. When they swelled up, chain started to bind and stick. Replaced chain and all was OK after that.