You'd think an organisation that can make something as freakingly awesome as the Raptor engine, could sort out their camera telemetry. If only there were some kind of mass array of satellites to provide reliable data connections anywhere....
Actually, SN15
did have a Starlink dish on it, although whether that was used for the video telemetry, or if that was sent through the pre-existing channels is unknown.
My guess is that they provide the downlink video as a PR exercise, but it's generally not as helpful as the realtime engineering telemetry information, which I'd bet is on a much more fault-tolerant link. Sensibly, they'd also send all the video onto some some of mass storage. A Micro-SD card attached to each camera could easily record the entire flight in HD quality, and they'd just need to be removed and collected afterwards, for a much more complete video record. The cost of that is small, but they also simply may not bother to provide better quality video later on, since the effort is problem not worth the marginal additional PR gains.