Season 3 is where the show went from "huge hit" to "cultural phenomenon." From Dany freeing the Unsullied at Astapor to the devastating (The Rains of Castamere), you need a format that does justice to the cinematography.
While Season 3 didn't have official extended cuts like Season 1, many high-quality MKV releases include the "In-Episode Guides" or commentary tracks as separate audio streams. You can watch the episode while hearing David Benioff and D.B. Weiss explain how they pulled off the Dragon CGI. game of thrones season 03 mkv