From his Instructor page:

A B-bender is a device connected to the B string of your guitar. It raises the B a whole tone to a C# like the pedals on a steel. One easy way to look at it is - Its like a whammy bar that whams up the b string only; and returns it to its original pitch. There are several different types of B-benders, Hipshot&Higgins are two external mount benders (mounts to the outside of your guitar), and fender makes a nashville tele with an internal system. Internals work off your strap mount beside the neck. Externals work either from a rod that runs to your hip , a palm pedal (like a whammy bar), or a cable attached to you strap.