So this view shows you the entire clip as a whole, with the part that's actually appearing in the movie highlighted between these two white bars. To get to it, right click on the clip, and choose Show clip trimmer, or use the keyboard shortcut of command backslash. But if you want more precise control in terms of picking exact frames to start, or in the clip, you'll have to use the clip trimmer. In many cases this is all you really need to do to add frames back to the beginning, or end of your clip. Now if you accidentally made the clip too short, or if the clip was too short when you dragged it in, you can deselect it, and just drag the edges to make the clip longer, or shorter again.

So with that selection made, I can choose modify, trim selection, or I can press option forward slash, and doing that trims away everything, but what I have selected, and remember you're never damaging your original footage when you do this, the complete uncut version of the footage where this clip came from, is still sitting safely here in the event browser, and again you can see the portion that I used, highlighted in orange.

So I'll skim until I come from behind the trees right about there, hold down r and drag to the right, and I'll select until I just run off screen right there. So I'm going to hold down r on the keyboard, and drag to make my selection of the area I want to keep. and I think in this case, I don't need the part at the beginning where I'm hidden by trees, and I also have too much time at the end after I run off screen. For example, after reviewing this clip in my project, where I'm running over this plank bridge, I've decided that it goes on for too long, so there are a couple of ways we can trim this clip, first, I'm going to skim through, and find the portion of the clip I want to keep. As you work on assembling your movie, there going to be a lot of times, when one of the clips you've added turns out to be too long or too short, maybe you accidentally left out some of the good action in the clip, or maybe after looking at the clip in the context of the rest of the movie, you determined that it goes on for too long, but that doesn't mean you have to go back up to the event browser, reselect the clip, and then drag it back in again, all you need to do is trim the existing version of the clip in the project timeline.

How to crop a video imovie