When the vibrator tunes to the resonant frequency of the system, the reactive load impedance cancels out to zero by virtue of the inductance reactance (mass of the system) equalling the compliance or stiffness reactance (elasticity of the tubular).
His role is highly unusual in that he had unsimulated and very graphic sex with his co-star Margo Stilley including genital fondling, female masturbation, with and without a vibrator, penetrative vaginal sex, cunnilingus and fellatio.