iski - clearly you must realize that the vehicle in the Youtube video is not a Mattel Big Wheel (looks like a rice burner to me) but some shallow attempt at a cheap copy.
The Center of Gravity on the Big Wheel was located well below the Axis of Evil which would prevent this type of accident. Big Wheels did suffer from a few other maladies though, the previously mentioned front wheel flat spotting, occasional severe pedal over-rotational torque shearing, the poor ergonomic consideration for BSR's and the unfortunate routing of the exhaust directly into the driver's left nostril. Most of these problems were addressed in later year models. Unfortunately, Mattel's brief experiment with the creation of the CTO division (Custom Trike Operations) and the introduction of the Screaming Turtle powertrain created exhorbitant business losses as well as numerous wrongful skinned knee lawsuits, forcing them to scuttle the entire operation.