and playing chopin's waltz https://www.youtube.com/watch?v=SfKqzN5MZYU is also quite easy
One of my favorite Victor Borge bits.
If you're having trouble with scale passages, you should practice scales as an exercise. In this case C major since that's what's in the piece.
With scales you need to work to ensure evenness. Beginners usually accent whatever note the thumb falls on, which is rarely what the music calls for. To counteract that, you need to decide yourself which notes to accent. It's actually easier to do that than to try to play all the notes exactly the same.
So you can accent every fourth note, doing 4 octaves up and down so it comes out even. Then try accenting every third note.
Or you can do acciacaturas, which I've described here before. That's where you play the scale with a dotted rhythm, first in groups of 2, then 3, then 4. Lengthen the first note of each group, then play the other notes very quickly.
So like C.... DE..... FG.....
or C....DEF.... GAB.... CDE....
building up to C... DEFG... ABCD....
Make sure you hold the first note for long enough so that it's easy to play the following notes quickly. And of course always use the correct fingering for the scale. That means you'll be turning the thumb under during the fast groups, but that's kind of the whole point...