Hes hooking it up to an external traxxas BEC but without any knowledge of the traxxas BEC specs or pics as to how it was hooked up, videos of what its actually doing, etc its hard to even take an educated guess as to what it could be.
What ESC, What servo, what battery, what are the specs on the traxxas ESC? Hard to answer that question without more info.
On a side note, I'm not sure why anyone would pay $40 for a Traxxas BEC when Castle sells a 10A BEC for $25 and its programmable. I can't find one website, including...