Thanks Wayne, Carl, Liz. Already in withdrawal...we need another one!!
Wayne, the exposures in the first 2 clips were done with a device called "the Little Bramper". It works by smoothly varying the bulb in millisecond increments. In addition you can step the ISO (manually) and it smoothly adjusts bulb to compensate. Gives you around 12 stops of latitude. Midday -> Midnight is around 20 stops, so you still end up a bit short for entire day -> night sequences. Unfortunately it's only available/works with Canon DSLRs.