Heres the solution:
Download these three files and place them in C:\Program Files\Mozilla Firefox\plugins
http://www.dlldump.com/download-dll-files_new.php/dllfiles/N/npdsplay.dll/3.0.2.629/download.html
http://www.dlldump.com/download-dll-files_new.php/dllfiles/N/npwmsdrm.dll/9.00.00.3250/download.html
http://www.dlldump.com/download-dll-files_new.php/dllfiles/N/npdrmv2.dll/9.00.00.32508/download.html