There’s one thing you should do before shooting a video on your iPhone: turn on Airplane Mode.
Airplane Mode will disable cellular service and WiFi. Why is this important for video? You don't want a phone or FaceTime call interrupting and stopping your recording. Mom, I’m working right now!
To turn on Airplane Mode, swipe into Control Center (from the top right on iPhone X and bottom from all other iPhones) and press the airplane icon. This will limit all incoming calls or messages from cellular and WIFI.
Alternatively, you could use Do Not Disturb, but make sure you know the specific settings on your phone. I use DND often but allow my family and close friends the ability to get through. And they would be the ones who would most likely call me anyways, so I opt for Airplane Mode.
But when recording a live video, I need to have connection to the internet so I head into the DND settings and turn off repeated calls and allowing calls from favorites (see circled settings).