If you are facing problem with the multimedia buttons when running Banshee then follow these steps.
Steps Go to Settings > Keyboard > Application Shortcuts Click Add Then type the commad Then press the shortcut button or** the media button**
Commands
banshee --next
banshee --previous
banshee --stop
banshee --toggle-playing
These settings are for Linux Mint. But the same process can be followed for almost any kind of linux distro.