As you move the video position slider, the left preview panel displays the input picture, while the right panel displays the output one (after applying all video filters, resizing, cropping and rotation). Bigger pictures are resized to fit, so you can always see the entire picture. To view the full-size picture click on it. To close the full-size preview click on it.

Click File > Save Input Screenshot to save the current input picture.

Click File > Save Output Screenshot to save the current output picture.