Castle has accompanied
Josh Groban and
Andrea Bocelli during Seattle performances. Since 2016, Castle has produced music videos, covering music such as "
Over the Rainbow," the theme from
Stranger Things, the theme from
Game of Thrones, and "Never Enough" from
The Greatest Showman. In September 2016, Castle organized a charity challenge. At the end of a video, he encouraged viewers to post a picture of themselves giving to a local charity on social media for a chance to be featured in an upcoming music video. Other examples include music from
Star Wars,
Cinderella, and
Moana. In 2018, Castle performed a duet with gay singer-songwriter
Tom Goss of
Ed Sheeran's song "
Perfect". == Personal life ==