There's a list of iMovie keyboard shortcuts under 'Help' on the top-line menu: it's "iMovie HD Keyboard Shortcuts".
But iMovie doesn't work on In and Out points selected from a longer clip, in the way that Final Cut Express and Final Cut Pro do.
It was originally envisaged that iMovie, as a simple editor, just lets you cut and join clips, with optional Transitions, Effects, etc.
There are Crop Markers which can be used: just put your cursor beneath the blue(?) Playhead line, just under the playback window, and a pair of triangular crop markers will appear. If they don't - just hover for a moment at the extreme left just beneath the playback window.
The crop markers can then be dragged to any positions, and Apple ('Command')+
K will then crop that selected video section. This can be undone with Apple+
Z.
The crop markers can be dragged anywhere, or you can click on one and use the usual keyboard shortcuts of left and right cursor key to move one a frame at a time, or Shift+left/right cursor key to jump 10 frames at a time.
It wasn't originally anticipated, with iMovie, that people would import longer sections of video than needed (..unlike professional shooting and capture..) and then choose just briefer sections within those long clips. The thinking behind iMovie was "cut out and throw away", not "identify shorter section and use that, while secretly retaining full duration of original clip".
It's only with the current iMovie 5/HD that the background handling of clips now approaches FCE and FCP, giving reliable "non-destructive trimming", so that crop markers can be used to set 'wanted' sections, and other sections remain behind invisibly, in a robust Trash can, "..just in case".
You can 'Split video at Playhead' (Apple+
T) ..which is what I generally use for editing, but you have to manually drag crop markers to where you want them. It's a historical thing.
You're really asking for a shortcut to set a crop marker to the Playhead position. Why not use Feedback to
ask for one in the next version?
But sorry; I don't know of any keyboard shortcuts to do what you want.
Maybe someone else does, though..
