So it seems as of last week Firefox released a new version (52) which pretty much breaks all browser plugins apart from Flash (which is what rendered Chrome useless for this not so long ago). This means you may keep trying to install the WebComponents plugin but it does nothing. Thankfully there is a fix:
How to use Firefox v52 to live view Hikvision device

Edit one all versions for mac. NPMedia plugin 1.0 Ask for webcam IP After signing into a Hikvision camera, the first page always asks whether to trust the plug WebVideoPlugin. After allowing trust, live view goes active. Guykuo October 2017. Use your smartphone/tablet with the Hikvision 8 channel NVR DS-7604NI-K1-4P NVR to remotely access your cameras wherever you are by using the web browser to connect to your NVR. This can also be done on your PC and Mac by downloading the live view interface, making watching your cameras a simple task.

1. Install the plug in first.
2. Open a blank page of Firefox and input

Hikvision Web Plugin Mac Not Working

about:config (where you normally type the web address)
3 Press Enter. Click on the, “I Accept the Risk” Button.
Chrome

4. You will then be in the plugin section of Firefox.
Right click, then go to NEW from the dropdown list. You will have 3 options to choice from, you will need to select Boolean. Once you have done that, you will need to type the plugin name:
plugin.load_flash_only
Click OK and choose “false” for the VALUE.

Hikvision Safari Plugin

5. Exit firefox and reload the DVR/NVR web interface to 'accept' to run the plugin at the top of the page (all being well).
There were a few other steps recommended past this, but we have found this alone to do the trick.

Hikvision Web Plugin Mac

Adam

Hikvision Web Plugin Mac

Update 19th September 2018:
Apple Safari 12 and Hikvision cameras
One of the best features of an IP camera is the ability to simply view it within your browser. Unfortunately in order to do this though, you need a plug-in called web components. When you try to view your cameras on PC you are prompted with a message notifying you that you need to download the plug-in, however on a Mac, there is no such notification leading users to believe that their Hikvision cameras are faulty or possible not compatible.
Now, if you head over to http://overseas.hikvision.com/en/tools_82.html you will be able to download the Mac OS Plug-in. Installation is fairly straightforward. Once you have installed the plug in, you should be able to view your cameras within safari. Make sure you have 'Webcomponents' selected from the plug-in list though.
Everything should work from this point. If you experience any issues past this point, feel free to ask any questions below.