After all i tried the Video Viewer program that comes with the DVR at my clients home PC...Method TCP..On IP address field enter the name that Dyndns gave me..Port number the port that i have already open for Dyndns...User and pass the admin ones....and there you go i can view and monitor his office cameras through his home and the most importand i can record them at his home PC as well.
Thank you for your time and your info guys and i hope i help a bit the next one that will try this.
Cheers
Marios N.