Rather than trimming, have you tried simply cutting the long file and dragging the pieces onto separate tracks? Also make sure you create an audio track for each new video track, because if you only move the video component of your original long clip it might remain "linked" to its audio component which is still up top on the original track. It's dodgy to unlink video and audio components and then move because you'll likely fail to keep them lined up. (There actually is a way to keep them lined up without moving the audio too: place cursor at cut point, cut video and audio, unlink, move video track down to new track and snap against the unmoved cursor.) One of the main things to learn with Movieplus is always be alert to the status of the link and ripple buttons (far left above timeline). Don't do anything until you've checked they are both where you need them. It's a lesson I learned the hard way but now I always glance at those 2 buttons before I do anything. Linking is everything in a complex project - multiple select audio/video clips, right click, link or unlink. For instance, if you add a caption, text clip or title to a project, always take the trouble to right click/link it to the video clip it goes with, so that it will move with that clip when you insert and ripple.