You will see the Zoom logo down at the left corner of the window. Also when the toolbar is turned off.
If the toolbar is turned on, than it wil be vissible when you click the logo. If the toolbar is turned off, you can use the keyboard shortcuts to zoom in and out, to pan in the movie and to localize hotspots and activate them as well, if tey are availlable.
If you click the Help you'll get an overview of the possibilities.