Here is the source file from the video, but more importantly the Add-On. Just install it like any normal addon through the preferences->addons menu.
Here is a demonstration of a new Add-On I created that lets you create IK, Track To, Stretch To and Other Bone target constraints a whole lot faster! You can pick it up by becoming a Patron https://www.patreon.com/johnnymatthews or at my Gumroad Store https://johnnygizmo.gumroad.com/
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