I've put together in a video all the commentaries by Joss Whedon on the scenes with Summer Glau in Angel 3.13 'Waiting in the Wings', taken from the DVD's special features. This episode of Angel was Summer Glau's first acting role.
Angel's Waiting in the Wings was written and directed by Joss Whedon himself, who provides insightful commentaries on Summer Glau herself, the way the ballet scenes were filmed and tons of trivias, including Whedon's two favorite shots from the episode.
A Wesley fantasy scene was filmed in which Amy dances the role of Giselle while Wesley clumsily tries to dance around her. The scene had to be cut due to time considerations, but is on the Season 3 DVD as a deleted scene.