How much bandwidth usage?

I have a zmodo ZM-KW0001-1TB NVR Kit that has 4 720p Wireless cameras and I would like to know what kind of bandwidth usage it would take up? Do these kits take internet usage or is it all just local network usage? Thanks in advance.

Its about 1mbps per camera on upload, the cameras upload the stream and you download the stream even if you are on the same local net, that is one downfall I have with this system.

If the cameras actually uploaded their stream and then downloaded it again, how did my wireless cameras and NVR continue to function without any issue when my internet was out for almost a full day?

It records locally to the NVR but there is no local play back. It streams from NVR to the internet and them an k to you.

Before I purchased my NVR, I ran a speed test both while viewing one of my cameras both via the website and via the app. Via the website gave the expected result (a hit on both download and upload speed). Viewing via the app had no noticeable impact, indicating it was not sending the video up to the internet and back.