Beethoven's 9 symphonies all have had alternate arrangements made for each of them, most famously the arrangements for solo piano by Franz Liszt. For non-virtuosos, arrangements for piano 4-hands also exist, and some were even published during B.'s lifetime. For some reason I never come across recordings of these 4-hand arrangements, maybe because they are "too easy". Nonetheless I've always been curious and I found a few "amateur" vids on Youtube, among them this one:
The most interesting renditions of the symphonies for 4-hands that I found belong to "AeolianHall1's" recordings of player-piano rolls. Here are a few Beethoven 4-hands arrangements encoded on paper rolls:
1. Symphony 3, 4th Movement
2. Symphony 6, 1st Movement
3. Symphony 7, 2nd Movement
Though not a Beethoven piece, I have to include this gem:
"Danse Macabre" by Saint-Saens arr. by Liszt played by Vladimir Horowitz
I love these annotations and pictures...well done.