Hi
Left Click the overlay video to select it.
Click the "Effects" icon on the tool bar. This opens the Video Effects pane.
Click "Add Effect" at the top and select "Scale" from the list.
(Note: You can also select this from the drop-down list obtained by clicking the little down arrow in the toolbar next to the "Effects" icon. However some effects lose the "Force Aspect Ratio" choices going this route.)
Now you can alter the horizontal and vertical dimensions of the clip by placing different values in the boxes. e.g. 50% as each value will 1/2 size the frame. Note: THIS "Scale" option affects both axes of the image separately and will enable you to change the aspect ratio of the clip if they are different.
If you want to also re-position the clip as well as scale it then instead of "Scale", select "Motion" from the drop down list.
Here you can scale the clip in a similar way as above (but with only one value to enter the aspect ratio is not altered.) You can also move ithe image relative to the top left hand corner. A bit of experimentation with the values will show you how it works. The "Rotation" function will rotate the frame in degrees clockwise.
To the right of each of these effects is a box with a blue line across it. The length of this box (and line) represents the length of your clip and there is a vertical red cursor line with a bright blue "handle" at the top that can be dragged along to different points in the clip. The clip can also be played by clicking the start > button under the preview pane.
By clicking the green cross you can "Fix" the values you have chosen for the effects at the cursor line position. This "keyframe" is shown by a small square (or squares) on the blue line(s).
Moving the cursor line to a different point in the clip and choosing different effect values a second "Keyframe" can be created.
Your effect will play smoothly from one keyframe to the next.If don't choose to set any keyframes, the effect plays throughout the whole clip. Using keyframes allow you to start or stop the effect at any time in the clip.
If you have set any keyframes the small squares can be grabbed with the cursor and dragged to different points to alter the effect, the values in the boxes changing automatically.
You can create numerous keyframes at any point along the clip if you wish and create complex movements of the image in the overlay.
Just experiment a bit and you will see how it works. You can clear the keyframes for a particular value with the red cross. You can remove the effects with the white "X"
You can add more effects to the clip from the drop down list by clicking "Add Effect". Each one will have its own control panel.
Nat