There are multiple ways to make a video available to view on the internet. This topic covers a way that's easy if you already use Dropbox (Dropbox Basic is free for 2GB of storage). Dropbox is a cloud storage service that lets you store your files online and also sync them or make them available from your mobile devices and Mac or Windows computers. If you make a video and store it on Dropbox, you can share it by copying a link to it that is useable by anyone you send it to.
These help topics discuss various ways you can create your video on different platforms.
From your computer, you can copy a file to your Dropbox by going to https://www.dropbox.com and logging into your Dropbox account. Dropbox is structured like a real drive: you can drop things in to the main directory or you can create folders to organize them. Navigate to the location where you want to store your video and then drag the file's icon from the Finder (on a Mac) or File Explorer (on Windows) into the Dropbox directory view in the browser.
To share the video on the internet, hover over its listing in Dropbox and click the Copy link icon:
A panel appears with a preview of the link. Click Copy Link to copy it. This link defaults to being viewable by anybody with the link.
Finally, you can paste the copied link into the audition form's Link to Audition Video field.