"File Download" element corrupts .zip files

Hi,

Generally love the product. Having a problem with the "File Download" element though:

STEPS TO REPRODUCE:
1. Add a "File Download" element on a course page
2. Enter a link to a .zip file in the "Enter a URL or Browse for a file" field
3. Save the page
4. Navigate to that page in the course
5. Click the download link to download the .zip
6. Try to open the .zip file

ACTUAL RESULT:
An error dialog stating that the .zip file is corrupt

EXPECT RESULT:
Can open .zip file and view contents with no error

OCCURS:
- On any browser
- Regardless of whether I upload the file to my web server manually, or if I use the "browse" button to upload into the WordPress library.

URL I enter in "File Download":
http://www.robotframeworktutorial.com/wp-content/uploads/2015/05/more-readable-start.zip

URL I get in the browser:
http://www.robotframeworktutorial.com/?fdcpf=aByqGPZXGAzIOe5CIoCzkgwUxPf7jw39K-4H9T4W_ym8b0I1sLHWWSBasax-ShmzbACYXH1DFJwFX7THlusaqPU2ihU6Vm-WsPcKFFJGaOxW7x14dN3uEAQamM1YWyQw