I'm a Newbie: video focus d3300?

LucasLand

i'm new to photography and making videos with my newly purchased d3300. I've made 2 youtube videos with it and i'm frustrated on how to keep everything in focus. if you watch the 2 videos i've linked you'll see that when the subject moves the camera doesn't keep it in focus. any suggestions?
https://www.youtube.com/watch?v=vMC7rxFTkSQ

https://www.youtube.com/watch?v=0nBsVTWtuFk

Ironheart

You have three options. 1) Turn on AF-C 2) Half-press the shutter button to re-focus when the subject moves 3) Grab the focus ring and pull focus manually