This will depend on the camera manufacturer and expected video quality. In some cases, the camera will provide enough details at 100 Kbits/sec but in other situations, even 2 Mbits/sec would be not enough. Typically, we recommend at least 700 Kbit/sec for full HD streams to ensure smooth video, but this parameter is highly dependent on the camera manufacturer, codecs used, and expected video quality. In some cases, even 50 Kbit/sec can be sufficient, while for advanced features like face recognition or license plate reading a higher bandwidth is required.
For more information on how to calculate data consumption, please visit this page
For more information on how much bandwidth is needed for cameras, please visit this page