Help me make this cocktail party algorithm code from coursera's Machine Learning lecture work.

From : https://class.coursera.org/ml-005/lecture/4

[W,s,v] = svd((repmat(sum(x.*x,1),size(x,1),1).*x)*x') 

It was mentioned in the lecture that this algorithm requires two sound sources. Where is the two sound sources in this one line code? I only see x. Is that suppose to be a sound matrix having two channels?

I tried setting x to

[x, xfs] = wavread('track.wav') 

and when I run the code, matlab tells me that I'm out of memory. ( I have a 4gb ram)