The keyword refers to the second episode of Young Sheldon ’s second season, titled " A Rival Prodigy and Sir Isaac Neutron ," specifically in the context of high-definition home media distribution on a 25GB Blu-ray disc (BD25). Episode Overview: " A Rival Prodigy and Sir Isaac Neutron "
When users search for a "BD25" version of an episode, they are looking for specific technical attributes related to Blu-ray storage and playback: A Rival Prodigy and Sir Isaac Neutron - IMDb