Legend has it that in the days of the Shaolin Temple, there was a tunnel filled with 108 wooden dummies, and the monks who completed their training were required to pass through this tunnel as one of their final exams. Each one of these dummies performed a certain technique, which the "graduate" monks had to neutralize on their way out of the temple.
When the Shaolin Temple was destroyed, Ng Mui, the Buddhist nun credited with founding Wing Chun Kung Fu, escaped. In deference to her training at the Shaolin Temple, she incorporated a training set using a single Wooden Dummy. This dummy set contains 108 combat techniques, each one supposedly to represent the 108 dummies that were in the Shaolin Temple.
Whether or not these legends are true, it is true that the Wooden Dummy set in traditional Wing Chun is an excellent way to develop the skills and co-ordination needed to become a proficient fighter.
The Wooden Dummy is used to develop timing, arm and leg co-ordination, proper use and application of force, distance, judgement, footwork and to teach practitioners how to flow smoothly from technique to technique. It is also used to toughen the limbs, although this is not the primary function of the dummy.
Wing Chun Kung Fu is a system that does not rely on strength and brute force; rather it stresses development of skill and co-ordination to have the practitioner deflect and redirect an opponent's attack, while simultaneously countering with his/her own attack. Deflection and redirection is achieved with correct positioning, requiring good footwork as well as co-ordination of the arms and legs, so that they work together to redirect an oncoming attack yet leave the practitioner in a position to counter at the same time.
All fighting techniques in Wing Chun come from the techniques in the Wooden Dummy. Dummy training allows the Wing Chun practitioner a way to correctly train the body in performing techniques. The amount of power one uses at certain times of a technique, as well as the timing of delivering such techniques can be drilled repeatedly on the dummy. Speed is improved because one can drill a series of movements over and over, creating the muscle memories needed to perform techniques automatically. Accuracy is refined because the practitioner learns how to correctly position his/her body in relation to the dummy (i.e. opponent) so that both arms can be used simultaneously. Footwork and mobility are enhanced, as the practitioner is forced to move from one side of the dummy to the other, moving in and out as well as laterally. Although working with a "static" partner, the Wing Chun practitioner learns how to combine footwork patterns smoothly with arm movements that deflect and attack, developing skills that are mandatory for successful free sparring. There are 108 Wing Chun wooden dummy techniques, which are grouped into 13 sections. Yip Man thought that some sections were too dangerous to be taught publicly. Therefore, he deleted some sections. There were more sections.
Regardless of the style one practices, one always hears that to be a successful fighter there are certain qualities and attributes that one must acquire. Speed, power, timing and accuracy are always cited as requisites to reach your peak in martial arts. The Wooden Dummy of the Wing Chun system provides the practitioner a valuable tool to achieve those goals.
Regarding the Sliding Dummy Movie Clip
Most Wooden Dummies are rendered immobile by screwing blocks of wood to the top and bottom slats on either side of the dummy. The Dummy can't slide laterally. The dummy needs to slide to the left and right in order to develop waist strength (Yiu Lik). Also, giving the practitioner a chance to chase the Dummy for a little more realism.