That no one came forth with an exercise but me is beside the point.
In this case, I believe that no other exercise but Chopin's actual piu mosso passage will do the trick, that's why I didn't suggest any. I told you the principle: do not prepare the whole range of notes in one passage in one block because your thumb will hamper the flexibility of your fingers if you don't have really big hands. It's simple arm leading note for note and listening to the sound of music. In terms of a "technical" exercise, you could consider making
moderately fast trills (MM 88-120, 4 to the beat) between the fingers used in the passages, using the very notes in those passages.
But the main problems in your clip are:
1) the illusion that the piu mosso part should sound "fast", even at the cost of evenness and simplicity;
2) that the left hand does not get the attention it deserves in terms of musical line and tone; this goes for the whole piece, not only the piu mosso.
Listen, for example, to what Rubinstein does with this waltz in terms of voicing, phrasing and shaping (there is also a view of his playing from above, starting from 2:04):