Do you mean the song that he is scratching along to (left deck) or the sound that he is actually scratching (right deck)?
The left deck sounds like a looper (get one here:
http://www.studioscratches.com/QSU-LOOPER.zip).
On the right deck he is just using an "It's..." sample from Al Nayyiysh (The Soul) by Hashim (watch from 0.00):
You're gonna need some scratch tools if you're gonna scratch. Google "free scratch tools".
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