I know I am replying to an old post but I hope this helps.
The problem with Play back is that IE does not recognise the connection as secure. The easiest way around this it to setup the IP of you DVR as a "trusted Site" and remove security checks for trusted sites. Also ensure you deeslect the "must sign in with HTTPS".
It took me a while to figure this out but it is all to do with ActiveX (Thanks Microsoft)
I would be interested if someone has found another way of doing this or which settings in particular need to be disabled (there are too many to mess around with).
Keywords: AVTECH, IE, Video Playback, ACTIVEX, Remote View, Remote Viewing