A couple of misconceptions here:
Auto-unprotect does not decrypt. It simply removes the flags the Humax sets on HiDef material that prevent that material from being decrypted. You can decrypt StandardDef files by copying them to virtual - no need to wait for the files to be unprotected. HiDef files can be decrypted in the same way once the Enc flag, visible in the webif, has been removed by auto-unprotect.
For streaming, the Humax's built-in media server can stream SD files and HD files that have been unprotected to a suitable client*. The media server does the decrypting on the fly, so there is no need to decrypt files to stream them. Mediatomb (someone correct me if I'm wrong) does not decrypt on the fly. Its advantage is that it can 'see' and stream decrypted files from the virtual disk, which is inaccessible to the Humax server. Its disadvantage is that it cannot stream files that have not been decrypted. In practice, you will probably find the native Humax server to be more useful than mediatomb, which has been rendered largely obsolete by later developments.
*Sorry, I'm not at all sure what constitutes a suitable client on a Mac...