Cross platform desktop application

Create a cross platform windows mac linux desktop application. Have an on-line database and admin area that can store content - videos and text for the application. Videos and text can be added and deleted into three categories from the admin area. Membership details can be added stored read/downloaded deleted. The application will Pop up 3 times a day and alert the user to play a video from a selection for that time of the day, the video can be selected by the user text will be displayed along with the video. The application is registered to that user for 12 months thus has to be activated by key. The application will cease to be active if allowed to expire with an appropriate message. Warning to be displayed as the 12 month time period draws near. The user can pay to renew membership through the application with PayPal or link to the the online presence to a contact details page with form for direct payment. The user can be activated/renewed by the administrator through the online admin area. All graphics required will be supplied.