This website embeds videos freely available on the web. The assumption is that the uploader is happy for it to be embedded. It is sometimes difficult to ascertain whether the uploader is the copyright owner but sites such as YouTube allow copyright owners have their videos removed or to monetize videos no matter who uploads it.
If you are the copyright owner of a short on this site (and are sure that another member of your team did not give permission to upload a video) kindly email me and I will remove it. Not only is it your right to have control of your work but it's good to replace the old with the new anyway. There are plenty of short films out there waiting!