The Zoom Tool is located with the other drawing tools in the Control panel and indicated by the magnifier glass.

When the Zoom Tool is active, you can use it to select an area of the image you would like to focus on, by clicking on the image and dragging to define the area of interest.

Once zoomed, you can pan around the frame by holding down the shift key and clicking on the movie and dragging the mouse. When in you are in this mode, the cursor will change from a magnifying glass to a hand.

You can return to normal view from the zoomed in view by selecting Zoom to Fit from the View menu. You can also zoom in and out without selecting the Zoom Tool, be selecting 'Zoom In' or 'Zoom Out' from the View menu or by using the Keyboard Shortcuts.