You can use VoiceOver gestures to trim Camera videos and Voice Memo recordings.
On the Voice Memos screen, select the button to the right of the memo you want to trim, then double-tap. Then select Trim Memo and double-tap. Select the beginning or end of the trim tool. Flick up to drag to the right, or flick down to drag to the left. VoiceOver announces the amount of time the current position will trim from the recording. To execute the trim, select Trim Voice Memo and double-tap.
While viewing a video, double-tap the screen to display the video controls. Select the beginning or end of the trim tool. Then flick up to drag to the right, or flick down to drag to the left. VoiceOver announces the amount of time the current position will trim from the recording. To execute the trim, select Trim and double-tap.