The Complex Plane; De Moivre's Theorem

The following videos are from MathTV.com. Click the play button in the lower left corner of the video lesson screen.  It requires Real Player, a free download.
Polar form (also called Trigonometric form) of a complex number
Finding Products & Quotients in polar form
Finding Roots of a complex number

Taft College provides this video that also requires Real Player.

Dr. Jacci White of St. Leo University recorded this video that also requires Real Player.