Complex sentence: Astaire received a percentage of the films'profits, something extremely rare in actors' contracts at that time, and complete autonomy over how the dances would be presented, allowing him to revolutionize dance on film.
Split into simpler sentences: Astaire received a percentage of the films'profits, something extremely rare in actors' contracts at that time. Astaire was also given complete autonomy over how the dances would be presented, allowing him to revolutionize dance on film.