You can do this when the desired video clip is either in the Content's pane or in the Timeline or Storyboard, depending on the selected view. The first way to do this is to move the playback indicator to the specific frame in the video that you would like to capture as a single image. This can be done when you open the specific video clip or if it is in a sequence in the Timeline. The second way to do this is to go to the Play menu and select Play Storyboard or Play Timeline, depending on view choice. Then you pause the playback once it hits the frame of video that you want to freeze. Once you have done one of these two options, you go to Tools in the task bar and then select Take Picture from Preview. You also have the option of clicking the Take Picture button that is on the monitor, which is a nice tool if you will be taking a number of Freeze Frames. Once you have done one of these a window will ask for you to enter a title into the File Name box that will identify the name of this new picture file. Now you can just hit save and you will have a saved image that saved on your hard drive as a picture and will appear in your project as a single image.