So I only found out today that you can playback the radar weather forecast, and when you do, it has a really really nice smooth playback animation. I'm guessing this is because the forecast rain movement is continuously generated rather than read at intervals like past radar data.
Anyway, I think it would be a huge improvement to the radar if the past data was interpolated for smooth playback as well! Perhaps this would be trivial for the devs to enable?
Fingers crossed!