If the video is on your phone or camera, you need to create a backup. Upload to a cloud storage to make sure you don’t lose the video. If you’re using a camera, then you may need to upload from an SD card or other storage format.
Most of us are familiar with making a recording on a phone or camera, but the purpose of the video should be considered. If you’re just sending a quick note to a colleague, then you might just use the front-facing camera on your iPhone. If you want to make a more in-depth recording, you might consider things like lighting and an external microphone to create a quality recording with audio.