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I didn't watch the video, but I wanted to answer a few questions with facts, and with opinions.
First, dry sump lubrication. This is not used in most cars because it is complex, expensive, and not required. A dry sump system uses at least two oil pumps, one to scavenge the oil sump to a tank, and one to provide pressure to the oil system by pushing oil from that tank into it. Most have more than that, with multiple pumps in the sump or from the cylinder head(s). I believe that the latest-generation Porsche 911 Turbo uses one pump for each bank of heads, and two for the sump--but I could be wrong.
More pumps == more parasitic drain == lower fuel economy. But very little oil in the sump == less loss due to windage == more MPG. Both numbers are very very small, but generally driving the pumps is the dominant factor there.
Race cars and wannabe race cars do it so that they don't lose oil pressure when undergoing substantial G-loadings for longish periods of time. Like long sweeping corners. It's not worth the expense or complexity for most street cars.
Oil levels: A smaller amount of oil will get up to operating temperature more quickly. If there is a decent oil cooling system, particularly one that is thermostatically controlled (or exposed to a thermo-controlled heat sink, such as engine coolant), the oil will stay at the correct operating temperature and not overheat.
A faster oil warm-up means a faster engine warm-up, which improves fuel economy each warm-up cycle.
I have heard anecdotally that having less oil in the sump means the oil is easier to pump through the engine resulting in better fuel economy, but I do not buy that.
Note that engines that are primarily cooled by engine oil (and direct air flow) can be more sensitive to oil condition and temperature than conventional water-cooled engines. I do not think that the motorcycle experience cited above directly translates, except to old Corvairs and a number of old European cars (VWs, Porsches, and a lesser number of others).
Oil light and gauges: The oil light on your car does not mean the oil level is low. It means that the engine has already lost oil pressure (most of them come on at 7 PSI or even lower, which is less than your engine needs for just about any mode of operation) and that you need to pull over right now and figure out what is wrong and fix it! The loss of pressure could be due to a low oil level, but it could be other things.
The temperature gauges in almost all of our cars only measures coolant temp--that radiator fluid stuff. The oil temp will have no measurable effect on that unless you have a water-to-oil cooler, which is not that common, and even then it will generally be a small effect, difficult or impossible to notice on the notoriously insensitive stock gauges.
The stock gauges and lights on our cars should not be regarded as measuring instruments, but more as "HOLY CRAP SOMETHING BAD HAS HAPPENED" indications.
-soD
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