If you want to achieve the effects of a single frame within a motion video freezing for a certain amount of time in Movie Edit Pro, this is how it's done:

1.) Open Movie Edit Pro and load the video you want to apply this effect to.

2.) Locate the position/frame you want to freeze within the project using the play cursor. Make sure that you're working in timeline mode for the highest precision and best ease of use. The picture you want to freeze most now show up in the preview monitor.

3.) Now, you need to extract a still copy of this frame from the video into a graphics file. In order to do this, go to the following position in the program: "File" menu => "Export movie" sub menu => "Single frame as BMP (or JPEG)". This will bring up a simple export dialogue where you mostly just need to name the exported graphics file and specify a location for it to be saved.

4.) Right after you've confirmed the frame export dialogue to save the picture and you're back in the main screen of Movie Edit Pro, hit the "T" key on the keyboard, while the play cursor is still in the right position, to split up the video clip at that position (where you want to insert the still frame you have just exported).

5.) Hold down your left mouse button on the video object part to the right-hand side of the split and pull it further to the right to open up a gap that is as long as the time period you want to freeze the frame for. Now locate the exported still picture on your hard drive in Movie Edit Pro's media pool and drag & drop it down into the gap between the two parts of the video. Now you might still want to make adjustments as far as picture duration and video object positions are concerned and you're done.

This would be my approach. Hope it helps. This technique allows for great artistic possibilities.