Trim video length and adjust slow motion on iPad
In the Photos app , you can trim a video you recorded on your iPad to change where it starts and stops. You can also adjust the portion of a video that appears in slow motion when you record a video in Slo-mo mode.

Trim a video
Open the video, then tap Edit.
Drag either end of the frame viewer to adjust the length, then tap Done.
Tap Save Video to save only the trimmed video, or Save Video as New Clip to save both versions of the video.
To undo the trim after you save, tap Edit, then tap Revert.
Note: A video saved as a new clip can’t be reverted to the original.
Change the slow-motion section of a video shot in Slo-mo mode
Open a video shot in Slo-mo mode, then tap Edit.
Drag the white vertical bars beneath the frame viewer to set where the video is played in slow motion.
Tap Done to save your edits, or if you don’t like your changes, tap Cancel.