BTW in the suggestion about an alternative LW in the link, it doesn't require installation. Just drag & drop into your apps folder after mounting the dmg file. Choose the "nightly" build. But the media player is disabled as it's only a beta.

Oh btw, I presume you are able to open the dmg file right? If not, then it sounds like Disk Copy is not opening it but some other utility which can't do it properly. Disk Copy is found in Utilities folder.