We have added two improvements to a self-luminous LED stroboscope (a flashing point-like projectile developed for introductory mechanics): downsizing by replacing heavy and risky batteries with a compact and safe capacitor of several Farads (a so-called Super-C) and wireless control via ordinary IR (infrared) communications. Consequently, the device allows the real-time visualization of velocity vectors to be performed using a web camera under ordinary room light. In this paper, we describe the technical details and also a typical demonstration by reference to our 15 min show at Osaka Science Museum that analyses the swing speed of a tennis racket on the spot.