iMovie '09 brings back the capability to speed up or slow down clips, which went missing in iMovie '08. Select a clip and bring up the Clip Inspector by double-clicking the clip, clicking the Inspector button on the toolbar, or pressing the I key.
Just as with its last appearance in iMovie HD 6, you can move a slider to make the video play back slower or faster (indicated by a turtle or hare icon). The slider lets you choose several speeds: 12.5%, 25%, 50%, 100% (normal speed), 150%, 200%, 400% and 800%.
You can also enter a value into the text field to the right of the slider, and this is where things get interesting. You're not limited to the tick mark values on the slider, so you can set the speed to be 118% of normal if you want. The field below that tells you the clip's changed duration.
But you can also exceed the boundaries of the speed slider. Enter any number between 5% and 2000%:
Here's what 2000% looks like, turning this 23 second clip into a 4.5 second blur:
Tip: If you're not seeing a Speed slider, the video clip may need to be converted before iMovie can make speed adjustments. (This is the case with MPEG-4 video from Flip camcorders, for example.) In the Clip Adjustments pane, click the Convert Entire Clip button, wait a few minutes (because, as the button says, iMovie needs to convert the entire clip, not just the portion in your movie), and then the Speed slider is available.