Haven't watched it. I suppose it depends on how high/low the pressure was before. If it's way too low it makes a huge difference, if you followed the car manufacturer and then inflate a bit the gain won't be very big (but hey, less FC is less FC).

From what I have read, unless you go above 3.0 bar (300 kpa) it shouldn't get uneven (someone reports 3.5 bar and no uneven wear...) or even get a blowout. What does kill the tyre is too low pressure, because it heats up a lot (high friction). 42 psi is the official value from Renault it seems, but I too am scared to go any higher than that.

If the car gets bumpy and hops around/looses traction, then that is too much. Haven't noticed that though with the Kangoo, but your milage might vary.

Generally you are right, front is supposed to be higher than rear, also heavy load or high speed driving should have higher pressure. Not sure why it isn't that way on my Kangoo (values taken from Continental... they don't have a sticker on the Kangoo), but I can imagine that the rear is supposed to have a higher pressure because it is also a small transporter, thus carrying heavy loads.

Trying to watch the video now, but about the slowing down part wikipedia begs to differ:
http://en.wikipedia.org/wiki/Engine_braking
"Additionally, most modern engines don't use any fuel while engine braking which helps reduce fuel consumption.[citation needed] This is known as DFCO or Deceleration Fuel Cut-Off."

put your gear to neutral while your car is moving is not recommended

if you are driving AT car, this is not recommended as well because engaging to neutral gear while the car is moving can cause excessive wear to the gearbox

Mythbuster also say to roll down your window and switch off your A/C when travelling slower than 45mph (around 73 km/h), which is not advisable when in a traffic jam during daytime, where your blood might boil and then you will explode.