multipart/x-mixed-replace images are sometimes used for streaming video for webcams. They can run infinitely long, consuming network bandwidth and draining a user's battery on portable devices. It would be nice if we had a facility to pause mjpeg streams and then later reload them. Clients could suspend these streams if they pause background tabs, for example.
<rdar://problem/7560990>
I am working on this.
See also: bug 23402.