Robert Sabuda on how he discovered pop-up books and how he had to "make-do" because he was a pioneer in the genre.
Kadir Nelson, who paints prolifically in acrylics, also has illustrated more than 2 dozen children's books and is a two-time winner of the Coretta Scott King Award for illlustration. In this video he discusses his goals and process.
Matthew Reinhart discusses his creative process.
Tour Mo Willems studio in his Lunch Doodles -- designed to help young children handle the pandemic.
These are just a few examples of the types of videos you can find by Children's illustrators. There are too many excellent artist videos to even begin to list them here. So take your favorite illustrators and don't forget to search for their videos!
You can also search for interviews with illustrators online such as this one for Rafael López (click the link for the full interview with plenty of illustration examples):
Chris Van Allsburg on Drawing Jumanji
David Wiesner talks about creating his book Mr. Wuffles.