Firstly, Professor Blacher recommends playing the piece a little faster and "in 4". Then they work on dynamical aspects, phrasing, color and sound, among other topics.
Profesoor Blacher also gives to the student some indications about weight and accents, character for the long notes, articulation, attention to the harmonies or rhythm, mainly.
Finally, Kolja Blacher explains her some musical issues related to the bow, tension and connection, as well as rapport with the piano/orchestra.