Both films combine biographical information with clips of musical performances and interviews with historians and musicians. The Beethoven film was perhaps a bit more interesting than the Mozart, I think in part because the impact of the film Amadeus makes the life of Mozart a bit better known than the life of Beethoven. Although I had seen the film Immortal Beloved which covers the basic facts of Beethoven's life. But "In Search of Beethoven" suggests the identity of the Immortal Beloved is Antonie Brentano, rather than Beethoven's sister-in-law.
The Beethoven film doesn't mention the movie "Immortal Beloved" but the Mozart film does make a reference to Amadeus (as "the Foreman film") when somebody complains about its inaccuracies. I think they'd have to mention it, since so many people get their concept of Mozart's life and character from that movie.
One thing the movie got right was Mozart's love of scatology. This facet of Mozart's character was little-known right up until, probably, Peter Schaffer's play AMADEUS, which was the basis for the movie. If anything though, the movie under-plays how dirty Mozart could talk. There is an entire Wikipedia entry devoted to Mozart and scatology. Not only did he write dirty things to his family and friends, he wrote scatological music. And Mozart's family liked to talk scat too - the movie "In Search of Mozart" quotes Mozart's mother, in a letter to Leopold Mozart, concluding with the phrase: "shit into your bed and make it burst," a phrase that Mozart uses in his letters as well.
The take on the scatology from "In Search of Mozart" is that people just spoke like that in those days, and I think this may well be, especially since in that time they did not have the luxury of flush toilets or toilet paper and had to cart their excrement off-premises themselves, and so something they had to think about more than we do today. Interesting essay on the history of toiletry here.
The Wiki article has another suggestion - that this is just the way Germans talk - right up to this day.
The same article has a funny footnote about some people's inability to accept this aspect of Mozart's character:
Margaret Thatcher, who as Prime Minister of Britain was appraised of Mozart's scatology when she made a rare visit to the theater to see Peter Schaffer's famous play Amadeus. Director Peter Hall relates: "She was not pleased. In her best headmistress style, she gave me a severe wigging for putting on a play that depicted Mozart as a scatological imp with a love of four-letter words. It was inconceivable, she said, that a man who wrote such exquisite and elegant music could be so foul mouthed". I said that Mozart's letters proved he was just that: he had an extraordinarily infantile sense of humour ... "I don’t think you heard what I said," replied the Prime Minister. "He couldn't have been like that." I offered (and sent) a copy of Mozart’s letters to Number Ten the next day; I was even thanked by the appropriate Private Secretary. But it was useless: the Prime Minster said I was wrong, so wrong I was." Source: Hall's preface to Amadeus (Schaffer 1981).
One of the best parts of the Beethoven bio movie is the section on what they call "An Epic Concert" - Beethoven arranged an all-Beethoven concert in 1808, during which he premiered his 5th Symphony. Here is the program:
The Sixth Symphony
Aria: "Ah, perfido", Op. 65
The Gloria movement of the Mass in C major
The Fourth Piano Concerto (played by Beethoven himself)
The Fifth Symphony
The Sanctus and Benedictus movements of the C major Mass
A solo piano improvisation played by Beethoven
The Choral Fantasy
The word is that the audience was too cold and tired to fully appreciate what they were hearing. But clearly it was once of the greatest concerts ever performed.