If you are using a linux/unix box (or have unix tools ported to windows), there is a command called "strings" that extracts printable ascii content from binary files and dumps it to stdout. Try this shell command on your file:

 strings yourfilename.dcd | less
[download]

And of course, you can redirect stdout to some other file, in case that helps you get your work done.

(BTW, I don't know what's up with that download link you provided. I couldn't seem to get any "dcd" data file, but I did get an invitation to spend money for some service that I presumably don't need.)