You need the current shockwave flash plugin. There is a problem with flash on Linux, and sound, that can be solved by compiling and installing the flashsupport.c library.
Compile and install as follows:
cc -shared -O2 -Wall -Werror -licuuc -lssl flashsupport.c -o libflashsupport.so
sudo cp libflashplayer.so /usr/lib
I cannot provide the code because it makes this post larger than the site permits. But if you google for it, you will find libflashsupport at the Adobe site.