 <p>There has been filebrowser demos out there written in Silverlight but they would run with elevated trust.</p> <p>That means that you would have to make the user immediately suspicious of your application when they first run it.</p> <p>It's probably a better user experience to just have a well worded error message for when the user runs out of space. </p> <p>Another option would be to try an increase the isolated storage quota by the size of the biggest video available.</p> <p><a href="http://msdn.microsoft.com/en-us/library/system.io.isolatedstorage.isolatedstoragefile.increasequotato(v=vs.95).aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/system.io.isolatedstorage.isolatedstoragefile.increasequotato(v=vs.95).aspx</a></p> <p>Then when that fails just let the user know that no more space can be allocated for the app had that he may need to delete older videos.</p>