Open the camera:

If needed, adjust the settings:






While recording, you can:




To start, tap 
You'll see two counters, one that shows the duration of the recording and another that shows the duration the video will play when sped up.

To record one video using two cameras (selfie and one of the rear cameras):

Review the preview and adjust as needed:







You can also:
If you're having issues, try these troubleshooting steps.