I created an assignment that asked students to record themselves (either video or just audio) reading a text out loud (this is a course on pronunciation of Italian). When I select 'speed grading' only one of the four videos uploaded so far appears. If I press 'download', I get the compressed files but when I click on them they do not open. The message tells me I am at the incorrect website or I need to refresh the page (which does not work). Are there any special instructions for students to upload the media assignments?