The M4B format is typically associated with audiobooks and podcasts, suggesting there might have been confusion or a mislabeling of the file. The standard video file formats for TV episodes would more commonly include MP4, MKV, etc.
Since M4B is an audio format, you will not see video. The file size will be much smaller (usually 40MB–80MB depending on bitrate), but you will rely on the dialogue and laugh track to follow the story. young sheldon s02e01 m4b