I did a bit of testing with mplayer and I was unable to play the stream produced by my ip camera, but vlc managed fine.
I found this link useful for finding how to directly access the video stream of my ip camera: http://wiki.micasaverde.com/index.php/IP_Cameras
I estimated that @ Standard Definition I need around 28MiB of disk space per minute of recording time.
Keeping a weekly history before rewriting would require about 270GiB per camera.
I finally got the ftp upload on movement detection to work. I could probably have that trigger vlc recording on the camera and just forget about looping.