There are several ways to fast-forward and rewind in QuickTime Player so here is another one, that works on 10.7 or later. Clicking and holding the Play/Pause button for several seconds replaces the control with a slider. Drag the slider to the right to fast-forward and to the left to rewind. The speed, which is displayed in the upper left corner of the video, is controlled by how far the slider is dragged. Once the mouse button is released, fast-forwarding or rewinding stops.

[kirkmc adds: And if you have a trackpad, this method is even easier.]