Bob WItt and Cy Berg are a couple of Vaudeville musicians who sing a couple of songs on an early Vitaphone short. The two songs are Honolulu Hula Girl and Hello, Aloha, How Are You? The musicians do not move about at all - Vitaphone did not allow movement. The main thing that recommended Vitaphone was that it was a sound system that allowed sufficient amplification for an entire movie theater.
These two perhaps starred in the first ever "Making Of" documentary when the filming of this short is featured in a Vitaphone short ABOUT making a Vitaphone short - "The Voice From the Screen". If they seem a bit stiff here, watching that short will maybe show you why, since they are being directed by technicians who mainly want to get a good recording and are not interested in a natural performance.
The "Witt & Berg" short was one of several Vitaphone shorts that played during the premiere of Don Juan in 1926, which was the first feature film to ever use Vitaphone, although at this point it was only used for the score and sound effects.
This short is available on The Jazz Singer three disc set, along with many other Vitaphone shorts that have been restored.