Play sample file as inline and files from my account as attachment

Question

I am working on the downloadable products.i want my preview file on the frontend should play and customers should able to download the products from their account from my downloadable products.

I know their is one configuration given by magento. Under Sys > Config > catalog > Downladable Information. use content disposition to inline both preview and products from my account will play.

and if i use content disposition as attachement then then preview file and products from my account downlad as attachment

Now actually i want preview to be played (inline) and products from my account should be downladed (attachment)