Well to try and make sense of this and to cut out the possibilities ya would need to see how the fuel float sits inside the tank and how the tank is structured on the bottom half to see if possibly the tank maybe be smaller on the bottom half. Considering the car is not very big space is an issue in building these cars. Now I know my AP1 gauge goes down quicker in the bottom half of my tank but not overly fast. As for the video of you filing up its possible that the sensor is having a possible delay reading your fuel level, this is done so when driving your car on the street and you have a sudden on come of "spirited driving" that your gauge reads more accurately by reading slower so the sharp turns and acceleration and deceleration doesn't affect your fuel gauge reading. Giving the Gauge a delay like so gives the fuel in the tank more time to level out and read more accurately. But if your gauge reads accurately when the light comes on then maybe its ok.

 

Personal comments removed, more comments on fuel gauges please

I find mine will plummet suddenly on occaision.

 

Seems like its a normal thing. On a friends Tahoe, it'll read empty parked on an incline. After a few miles driving straight, it'll read a little less than half a tank o_O that bad.

 

I know Full Blown told me to make sure when I put my pump in that I watch the orientation of the sock as it can really mess with the guage. Maybe LJ has a more in depth explanation

 

i have a MY05 also. And I noticed the exact same thing as you.
Takes a long time to finish the first two thirds of the tank then it just drops pretty quick the last third.
Just thought it was normal so I try to make sure I fill up before i hit 1/4 tank.