I record here arcana which some readers will be unaware of. There are the general simple Unix commands which I defer. OS X 10.9.4 (at least) quarantines the package from this site. The following shell commands overcome this. 
cp /Volumes/DMD2/DMD2.pkg .
xattr -d com.apple.quarantine DMD2.pkg
open DMD2.pkg
There may be a better way.

I complain here about Apple’s Installer application in this context.

The file /Volumes/DMD2/uninstall.command is also quarantined and should probably be preserved unless you preserve the file dmd.2.066.1.dmg from which it can be retrieved. I did this: 

cp /Volumes/DMD2/uninstall.command ~/Uninstall_D
xattr -d com.apple.quarantine ~/Uninstall_D
to be run in the future if you should want to undo this installation: 
./Uninstall_D

I think that that command leaves behind material that supports programs you may have built in D such as shown in this snap shot.