Thanks for your work so far - I realize this thread is quite old.
The RTSP stream can be locally obtained by the links in D-Link DCS-8000LHV2 integration - #6 by bjornefar
For getting it from the cloud one would have to debug the mydlink.com page. There is an
rtsp_player_release_0.2.js which accesses rtsp://mp-eu-rtsp-8.auto.mydlink.com:443/alexa/profile.0?cid=XXXXXXXmac=XXXXXXXXX in my case. Opening the URL in VLC does not work straight away, I assume some session handling has to be done, but for me viewing the stream locally is enough so I did not debug further.
What I would like to achieve is getting the motion detector of my DCS-8627LH as a sensor into HA. Yet, I’m not 100% that it is even exposed somewhere. I keep digging, if anyone has any pointers it would be appreciated!