yer just bending from 19 to 20 then back to 19 without repicking, kinda like a superwide vibrato.
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just bending...

i found it easier to play it on the e string though

15 pull off to 14 3 times then 15 on the B string.

i've done a (poor quality, quickly filmed) video if it helps you, it might do... not quite sure.

here: http://www.youtube.com/watch?v=PZuemH3xEVs
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