I don't know where they get the "5 seconds" of latency for dash videos. There's definitely a startup latency, but it's not 5 seconds, and can be avoided with some simple techniques.
They're thinking of live dash streams. Eg. how many seconds from video camera to screen.
I can see it would probably be possible to get low latency, but without a fancy server stalling connections till frames become available, flushing on frame boundaries, etc, I can't see it working. Try doing such things with a CDN like cloudflare to support lots of users...
Also, for true streaming, timing should be done by the camera. Ie. If the cameras frame rate is 0.0001% slower than the 60fps advertised, the display device should slow down to match.
MPEG-DASH has no ability to do this, and would lead to a "buffering" gap for a second every few hours of playback time.
