In Apple Support's online article:
Take videos with your iPad camera – Apple Support
Eg: says:
Capture a time-lapse video
- Choose Time-lapse mode.
- Set up your iPad where you want to capture a sunset, traffic flowing, or other experience over a period of time.
- Tap the Record button to start recording; tap it again to stop recording.
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"Record a slow-motion video
When you record a video in Slo-mo mode, your video records as normal and you see the slow-motion effect when you play it back. You can also edit your video so that the slow-motion action starts and stops at a specific time.
- Choose Slo-mo mode.
- Tap the Record button or press either volume button to start and stop recording.
- To set a portion of the video to play in slow motion and the rest at regular speed, tap the video thumbnail, then tap Edit. Slide the vertical bars below the frame viewer to define the section you want to play back in slow motion.
Depending on your model, you can change the frame rate and resolution. The faster the frame rate and the higher the resolution, the larger the resulting video file.
To change slow-motion recording settings, go to Settings > Camera > Record Slo-mo."