Entertainment Weekly shared a great video of John Green with the actors on the TFIOS set (featuring some clips from his previous videos) as he shares the experience of being a part of the adaptation!
John also talked about why family relationships are such an important part of the tale:
That was a gift given to me by the kids I’ve known who have been sick. They wanted to know that their families would be okay. You don’t want to hurt people you love. When you’re sick, you’re forced into that position.