Musical Interlude: Maurice Ravel's Bolero (by Bruno Bozzetto)

Wiki:

Allegro non troppo is a Bruno Bozzetto animated film released in 1977. The film is a parody of Disney's Fantasia, though possibly more of a challenge to Fantasia than parody status would imply. In music, an instruction of "allegro ma non troppo" means to play "fast, but not overly so". In the context of this film, and without the "ma", it means Not So Fast!, an interjection meaning "slow down" or "think before you act" and refers to the film's pessimistic view of Western progress (as opposed to the optimism of Disney's original).

The film features six classical pieces:

Prélude à l'après-midi d'un faune by Claude Debussy

Slavonic Dance No. 7 Op. 46 by Antonín Dvořák

Boléro by Maurice Ravel

Valse Triste by Jean Sibelius

Concerto in C major for 2 Oboes, 2 Clarinets, Strings and Continuo by Antonio Vivaldi

The Firebird by Igor Stravinsky

The classical pieces are set to color animation, ranging from comedy to deep tragedy. At the beginning, in between the animation, and at the end is black and white live action film, displaying the animator (not the actual), orchestra, conductor, and filmmaker, with many humorous scenes about the (again, not actual) production of the film. Some of these sections mix animation and live action: for example, after the final number, the (animated) serpent (in colour) escapes into the orchestra pit, scaring the (live, black and white) musicians. In another, Mr. Rossi, Bruno Bozzetto's most famous creation is burned to death when his animation cel catches on fire.

The film has two versions, the main difference being in the inclusion or exclusion of the sepia live action sequences in between the classical pieces. The second version of the film omits these sections, replacing them with animated plasticine letters spelling out the title of the next piece of music.

And here's Allegro non troppo on the IMDB

[opening lines]
The Presenter: P:Ladies and gentlemen, you are about to see an unforgettable show, a film destined to become immortal, as immortal as the music which will follow, and which will be interpreted through animation. Beginning with his childhood fantasies, the greatest ambition that burns and swells in the soul of every creative animator is to illustrate music, to give visual form and color to its notes. With this film, we have finally succeeded in achieving this union of animation and classical music, a union we are sure is destined to live on throughout the history of film. A new and original film that has even astonished us, the men responsible, the men who, quite modestly speaking, can be called its creators. A film in which - in which -
[consults a cue card]
The Presenter: A film in which you will see the music and listen to the drawings. You might call it a film of magic, a fantasia.
The Presenter: [Phone rings - Presenter answers; the caller is not heard]
The Presenter: Hello. Yes. Who's speaking? Who is this? What do you mean, who am I? Who is it you wish to speak to? Eh? California?
The Presenter: [To camera] It's Hollywood.
The Presenter: [To phone] Hello! Yes! What? You've already -
The Presenter: [To phone] Hello! Yes! What? You've already -
The Presenter: Look, if this is some joke, I'm in no mood --
The Presenter: No, but- No, but- there must be some misunderstanding.
The Presenter: You're very ill-mannered...
The Presenter: That's right, ill-mannered and a liar!
The Presenter: Yes, I said you're a liar! A liar from California
[Hangs up and speaks to camera]
The Presenter: It's nothing. They're mad. Mad as hatters. They insist that our film - this is all so ridiculous - was already made by a certain fellow years ago. A certain someone by the name of Prisney or Grisney. Some American.
[Picks up phone again]
The Presenter: In any case, before you go around opening your big mouth, see the film first!