$ sudo apt-get update
$ sudo apt-get install gnash-ext-mysql 

gnash-ext-mysql is installed in your system.

Make ensure the gnash-ext-mysql package were installed using the commands given below,

$ sudo dpkg-query -l | grep gnash-ext-mysql *

You will get with gnash-ext-mysql package name, version, architecture and description in a table

gnash-ext-mysql package basic information: