August 9 is the 100th birthday of the conductor Ferenc Fricsay (1914-63). Along with many recordings, he left behind a fascinating documentary for German TV, showing how conductor and orchestra work together in rehearsal.
For about 40 minutes, we see Fricsay rehearsing a long time, but you can dip into it at any point. The music is familiar Smetana's "Moldau" (or "Vltava"), but Fricsay is totally engaged, despite his poor health: always bringing out some interesting detail, or encouraging or correcting the players, or indulging in some poetic metaphor ("The panther is ready to leap!").
At the end of the documentary, at about 44:00, you'll see the finished performance.