Gene vs. ..... anyone?

In 1950 there was a movie with Judy Garland and Gene Kelly'
Called Summer Stock.
In the movie is a dance with Mr. Kelly, all by himself.
In the movie it appears that he did it from start to finish without splicing different parts together.
In YouTube.com it gets choppy and might lead one to wonder.
But I will believe He might have had to start over a few times, but that he did get it right at some point.