BDMV is a file extension associated with Blu-ray Disc Movie (BDMV) files. These files contain video and audio streams, as well as other metadata, used for storing and playing back high-definition video content on Blu-ray discs.

The third season of Young Sheldon premiered on September 26, 2018. The first episode, "The Big Move" (S03E01), marks a significant milestone in Sheldon's life as he prepares to move to New Jersey to attend high school.

Regarding the BDMV file extension, it seems you might be looking for information on video files, possibly related to the episode.