All right, Beethoven is not the subject of this film. But he appears in one scene. Here's the decription of it...

A close shot of Beethoven shows him playing the last bars of his Appassionnata. Then the cameras pan out: Beethoven is playing for the Habsbourg court. Marie-Louise of Habsbourg-Lorraine sees the portrait of Napoléon, hung on the chimney-breast. She becomes green with rage... Soon calmed, she sits down.

Beethoven therefore plays the first movement of the Eroica Symphony. Marie-Louise recognises the music, gets up, vexed, and starts shouting again. But her father explains that she must marry Napoléon; Marie-Louise calms down again, and excuses herself to Beethoven...

Then a general of France, a diplomat, invited by the Court, begins talking to Beethoven: "Ah! You dedicated it first to Bonaparte!". Beethoven replies: " Ah yes... But then I crossed out his name... I wrote "Eroica - Symphony for a Great Man"... like that we can guess that it's for him... It's best that way "...

Thanks to Steve, passionately attentive, for this description

Technical Information:

Napoléon - Film realised by Sacha Guitry in 1955, produced by Clément Duhour.
With Daniel Gélin (Bonaparte), Raymond Pellegrin (Napoléon), Orson Welles (Sir Hudson Lowe), Michèle Morgan (Joséphine de Beauharnais), Gaby Morlay (Silvana Pampanini), Patachou (Madame Sans-Gêne), Jean Marais (Comte de Montholon), Erich von Stroheim (Ludwig van Beethoven), Yves Montand (Maréchal Lefèbvre), Jean Gabin (Maréchal Lannes), Danielle Darrieux, Pierre Brasseur, Serge Reggiani, Henri Vidal...
Duration: 140 minutes.

Eric von Stroheim, in the role of Beethoven

Available: 2 DVD of 90 minutes each.

A film from Autria:

DER MÄRTYRER SEINES HERZENS
The Martyr of his Heart (Der Märtyrer seines Herzens): silent film of 1918 on the life of Beethoven. The film was directed by Emil Justiz, and Fritz Kortner plays Beethoven…

The following film is Austrian, and exists also in French. It was presented at the Cannes Festival in 1949:

EROÏCA, a film by Walter Kolm Vellée, released in France in 1950. Ewald Balser plays Ludwig van Beethoven.

Here is another French film on Beethoven (thanks to Michel Rouch for his kindness):

LE MECANO DE L'OREILLE, ("The mechanic of the ear") by Gert Jonke, directed by Stéphan Barbarino and filmed for television.