I am having the same issue.
I have Yosemite 10.10.1 and installed the Hikvision plugin from: http://www.hikvision.com/Es/download_more.asp?id=1192
The plugin installs correctly.
When I try to see the cameras with any browser (Firefox, Safari or Chrome) it shows the following error:
"No plug-in detected."
I also tried using the Hikvision Desktop application from:
http://www.hikvision.com/europe/download_more.asp?id=1367
It asked me to install X11 Quartz, which I did. But still can´t see any video.
I must say that everything works perfectly with Android, iOS and Windows. My only issue is with MAC.
Can anybody help me?
Thanks,
-Diego