Thanks SouthernYankee for the reply.
My bad, yes NVR not DVR :)
The Dahua spec sheet specifies 8192Kbps on H264 (which is the highest rating) and 30fps @ 2Mp (which is also the highest rating). x 8 gives me 65,538Kbps (previous calc was wrong) which equates to 65,5Mbps (if google serves right...