The video is made by Your Sandbox and explains how to work with depth of field.
Here's a great tutorial on how to create the tilt-shift camera effect in Unreal Engine 5 by Your Sandbox.
In the video, the author explains how the sensor size affects the depth of field and how to make the near and far planes of your game's screen blurred.
The YouTube channel provides videos meant to help make games in Unreal Engine. "Anyone can make a game by themselves" – that's Your Sandbox's motto.
Here are some more great tutorials to help you grasp UE: