Most of the feeds are coming off of personal scanners. On occasion, the PD will contact the net site and ask them to take the feed down temporarily. They did that briefly during the incident in Big Bear earlier this year. Sometimes, the individual department will switch to a frequency the scanner owner doesn’t have programmed in, but that’s not too common. Most of the time, the traffic will be there, though with the increase in smartphone aps, takedown requests, or going to encryption may become more frequent.
BTW: The process usually adds a one to three minute delay to the traffic.
Interesting, thanks !