There is an inherent problem with the filter code. If you use the downloads shortcode in any other page then no downloads will display.
My solution was to create a link to the appropriate category for upcoming events. The user will then click on the event to purchase using the EDD Tickets interface.
Here’s the solution. Create a new category of the download as “Expired”. Once the event is over, add that category to the download. Here’s the shortcode.