Sorry for my delay, I was struggling to get the latest info.
Here you can find the latest
user manual for iVMS-4200 for Windows (for V2.8.2.2)
It's a huge manual.
If you Ctrl+F search for the term 'video loss' you will find that it is possible to configure actions in iVMS-4200.
I haven't followed the steps, I don't know whether setup will allow you to do so for many cameras at once.
NB
If you follow Hikvision you'll be aware that firmware releases, portals, etc have been a bit topsy-turvy lately, hence we've fallen behind a little in this forum. I hope today to make at least a couple of new posts with all the latest info I have for iVMS-4200.
In particular, as I still don't see a better 'no-plugin' solution coming from Hikvision any time soon, I think that more and more users will come to depend upon iVMS-4200 as their browser options become reduced. Mac-users especially are really struggling with browser compatibility between Macs and Hikvision.