Hardy - vdr-plugin-burn cannot install

[Geoff Horn]

Does anybody know how to get vdr-plugin-burn installed. It seems strange that 
the package exists but yet cannot be installed because of missing packages!

What does virtual package mean in this context? Does it means someone is 
working on it?

This is what I get when attempting an install:

  vdr-plugin-burn: Depends: mkisofs (>= 2.0+a19-2) which is a virtual package.
                   Depends: vdr-genindex (>= 0.1.3) which is a virtual 
package.
                   Depends: vdrsync (>= 0.1.2.2dev2+050322) which is a virtual 
package. or
                            projectx which is a virtual package.