Hi there Richi 
Welcome to our community!
WD Purple and WD Purple NV are drives specifically designed for DVR and NVR storage which makes them great for A/V data storage, recording and streaming. They have all the necessary features to safely record data from NVRs so you should be completely safe using either of the drives.
WD Purple NV drives are designed specifically for Network Video Recorder surveillance systems and are capable of handling more cameras where scalability is needed. They are also backwards compatible so they can be used safely in DVR systems as well. Check out more info here.
I also believe that this article would be an interesting reading for you.
Let me know if you need more information on our WD Purple series drives.
Captain_WD.
