To crop a clip in iMovie you need to click on the Crop button (usually the second button from the right between the i and microphone buttons), adjust the cropping lines in the viewer until you have the desired crop and then click on the Done button in the top right corner.
Double click the clip.
To reverse a clip in iMovie select the clip to be reversed, open the Inspector, in the Speed section click the Convert Clip button, and once the clip is converted tick the Reverse box.
To add a freeze frame still image to a movie in iMovie move the mouse pointer over the image, in the project section, you wish to freeze and right click (or press the Control key and click) and select Add Freeze Frame from the pop up menu. This will add a 4 second still clip into the movie. Double click on the new clip to show the inspector and you can change the Duration of the clip or add an effect to the clip. Moving the mouse over the new clip reveals a small blue options menu in the bottom left corner of the clip. From this you can select Cropping, Ken Burns and Rotation with which you can crop, rotate or scan across the still image - for example to zoom in on a persons face.
Almost all video editing software can reverse a clip. If it does not it is not worth having.
Click File and then Optimize Video
First drag the movie you want to do the commenty for into iMovie. Then record yourself speaking in another application on your mac, (watch the clip your speaking over while you speak over it so you know what your saying) then drag that voice clip over the top of the clip which you've placed in iMovie.
Mp4 is a good format for iMovie.
Opacity can only be changed with a Cutaway edit. Make sure Show Advanced Tools is ticked in the iMovie Preferences. Drag a clip from the browser over a clip in the project and select Cutaway from the menu of options. The added cutaway clip appears above the original clip. Double click the cutaway clip and you can change various settings, including the opacity, in the Inspector pane that appears.
To adjust the speed of a clip in iMovie hover the mouse over the clip that you have added to the project and a small blue button with a down arrow will appear in the corner of the clip's thumbnail. Click on the down arrow and select Clip Adjustments from the choices offered. In the panel that opens you have buttons to choose between Clip, Video and Audio. Click the Clip button and in the middle is a speed adjustment/reverse option. It may ask you to convert the video before allowing you to adjust the clip.
The duration of a clip can be extended in iMovie by selecting the clip, pressing the I key to open the inspector and changing the time in the duration box. If this is for a still picture you can tick the box marked "Applies to all stills" to change the duration of all still images.
you cant do that on an ipad unless you want to pay 20000 to buy the ipad
To crop a video in Premiere Pro CC 2017, you can use the "Crop" effect. First, select the video clip in the timeline. Then, go to the Effects panel, search for the Crop effect, and drag it onto the clip. In the Effect Controls panel, adjust the crop settings to crop the video as desired.