Okay kiddo, do you know what a classroom is? It's a place where your teacher teaches you and your friends learn new things.
Now, imagine that the classroom is the internet, and a teacher named Berkeley is teaching something really cool on it. But not everyone can go to this classroom, because they might live far away or have something else to do.
So Berkeley decided to record his lessons and put them on the internet for anyone to see. This is called a webcast. It's like watching a video on YouTube, but it's a special video made by a teacher to help you learn.
And here's the best part, kiddo - Berkeley's webcasts are free! That means you don't have to pay anything to watch them. You can learn from a really smart teacher without leaving your house.
So if you ever want to learn something new, like science or math or history, you can go to Berkeley's webcast and watch one of his lessons. Just don't forget to take notes, because there might be a quiz later!