Comment 17 for bug 281808

If you want to replace flash 10 with 9 (while waiting for the end of the never ending struggle w/ konq+flash):
1. Download fp9 from the archive: http://fpdownload.macromedia.com/get/flashplayer/installers/archive/fp9_archive.zip
2. edit /var/lib/dpkg/info/flashplugin-nonfree.postinst
 -comment (or edit) the lines that check the md5sums
 -change the references from flash...10 to 9
3. copy the chosen tar.gz to /var/cache/flashplugin-nonfree/install_flash_player_10_linux.tar.gz
4. run: sudo /var/lib/dpkg/info/flashplugin-nonfree.postinst configure

That will replace the fp10 in your system with fp9, while keeping the presently installed .deb in the present version. If you want to do this, you probably already know what to edit in the flashplugin-nonfree.postinst file.

I replaced the fp10 with the fp9r124. Youtube videos work, and even the myspace music player.

Probably instead of the steps above, you could just replace the file /usr/lib/flashplugin-nonfree/libflashplayer.so. I didn't test.