I wanted to merge two videos and it worked as bellow. Size for the both source videos was 320×240, and I also wanted the final output same as 320×240.
1. Run ZS4. Have the File button pressed. Single click on the file you want to import.
2. After analyzing is complete there will be a green down arrow. Drag this arrow to the lower left pane.
3. Click on the File tab and import 2nd video file as before. When you drag the 2nd file, the cursor color will be green when the place is correct. Drop it on the 1st video imported before.
4. Set the output file name. Click on Track => Export. Click on Browse and type the file name (typing extension .avi is not needed).
5. Set the output video’s size to 320×240. Click on the “i” button on MediaMixer Track and the Properties tab will appear on above pane. Click on the Width and Height field and type the value, then click Update button.
6. Set the Output Opacity of MediaMixer Track. Click on the “output opacity” button. In the “change” field above type 1 and click on the “=” button.
7. Set the 1st video’s output opacity to 1. Click on the 1st video track’s “output opacity” button. In the “change” field type 1 and click on the “=” button. The name of the video file is printed on the track.
8. Set the 2nd video’s output opacity lower than the 1st video’s opacity, let’s set it to 0.20. Click on the 2nd video track’s “output opacity” button. In the “change” field type 0.20 and click on the “=” button.
9. Check the preview by clicking the small yellow button on MediaMixer track. Click Cancel button to close the preview.
10. Now you need to select codec and save. Click on the small green button – compile/save, on MediaMixer track. The export tab will appear above. Click on the “export” button.
11. Codec selection dialog will appear. Click on the left or right arrow to select codec. I selected “IYUV/I420 YCrCb Planar”. After selecting the codec click on “enter” button. The conversion will start.
You may cancel the conversion by clicking cancel button, the output file will contain the converted video until the cancel was clicked. And finally, the converted output will be big, so there should be available disk space. You may later use other program to convert it again to reduce size.