Yes it is possible however it will not be totally unattended. A box will pop up and warn you about not be able to include the installation into the system restore. Then you have to choose wether to continue with the installation or not. The only reason you would have to have an installation in cmdlines.txt is if you need the registry changes of the application to go to all users (HK_Users). Media player installs to all users any way you install it, so just place the cmd in winnt.sif or unattend.txt. I hope this helps.