I would like to edit the length of video effects (instead of having the effect run through the entire segment of video, I would like to only use it for 3 or 4 seconds in the middle of the video). Please advise---I cannot find anything in the tutorials or in these questions which answer this. Currently, the effects run through the entire segment of video.
Many of the video effects are made with Keyframe Animation. If you have the Plus-version of MEP, lay an effect on a clip and study how it is made by activating the Keyfr. A. Then try to make the same effect on a part of your own clip.
Another way could be to cut "3 or 4 seconds" in the middle of your clip and put the effect on that.