Slow down the video
When you import a video or double-click the video you want to adjust the speed of in the list of "Added Clips", the "Preview/Capture" dialog box will pop up. Click the "Magic Functions" tab below the video preview box in the dialog box, and in the "Functions to apply to video" drop-down box in the "Magic Functions" panel, select In the "Slow Motion Effect" drop-down box in the "Magic Functions" panel, select "Slow Motion Effect" and set a value for the "Deceleration Rate" slider underneath it; the larger the value, the slower the video will be after adjustment.
Speed up the video
When you import a video, or double-click a video you want to adjust the speed of in the Added Clips list, the Preview/Capture dialog box will pop up. Click the "Magic Functions" tab below the video preview box in the dialog box, and in the "Functions to apply to video" drop-down box in the "Magic Functions" panel, select "Fast Forward Effect", and then set a value at the "Acceleration Rate" slider bar below it, the larger the value, the faster the video speed after adjustment.