The 1970s. Israel Philharmonic. Mahler. Christa Ludwig, a German, argues with Bernstein about tempo. Bernstein describes this passage as “always impossible” and suggests that the audience won’t understand the words anyway, so what’s the big deal? Awkward. For both. Conductor and soloist.
Bernstein is clearly the boss. Ludwig, however, is the specialist. They’re not at eye-level (Augenhöhe) with each other, but they’re pretty darn close. And Berstein accepts this.
Here is another clip with Bernstein and an orchestra. The second trumpet player and the conductor interact. See the very thoughtful comments from musicians with experience.