As written earlier, the decision in a forehead is to drain the stream from the cameras via an external channel somewhere.
There is another option, write in my experience:
1. put any software DVR, able to record video only on movement in the frame. thus, we significantly reduce the amount of generated video.
2. this recorder writes to a local video archive.
3. custom transfer new files to a remote server, for example cron for rsync or similar in a primitive way.
what we get:
1. reducing the amount of transmitted data by recording only on motion sensor.
2. storage archive somewhere locally files are generated and stored temporarily - i.e. it is actually a buffer.
3. this scheme can easily survive a temporary loss of connectivity and temporary drawdown of bandwidth.
I did it with motion and analog cameras, when the channels were cdma450/3g/wimax at the current speed can be completely and HD videos to merge.