Latest Firefox browser version have disabled the support for Shockwave and many other plugins by default. However, you can enable it again by tweaking the configuration:

1) Enter as the URL:
about:config
2) Right-click the mouse anywhere on the configuration variable list and select “New” > “Boolean”.
3) Name the new configuration value: plugin.load_flash_only
4) Set its value to “false”.
5) Close the configuration tab. In some cases you will also need to restart your Firefox browser.

After restarting, Shockwave and other old-fashioned plugins will be available again.