Sorry I never got back to you about the PoC gesture app earlier.
I've just tested out this new experimental app - cool idea!
I was able to get 'Wave to answer' and 'Wave to ignore' going easily enough when the TP was on my desk and on a chair closer to the window. I had to wave a couple times to get the desired response but found that if I move my hand across the light sensor for about .5 seconds around an inch above the phone it was pretty consistent.
I couldn't get the 'AutoLock' working consistently. If I cover the light sensor with a piece of paper or put the top 80% of the phone into a cloth bag it doesn't lock. A few times when I was covering the light sensor with my hand the lock screen flashed up but disappeared again without me having to unlock it.
It took a bit to figure out how to unlock the lock screen but from watching your YouTube video and playing around I can do it easily. It seems best to grab the phone between my thumb and index finger with my thumb on the lock icon (so it is green). Then I flick the bottom end of the phone quickly 90 degrees and back. It is harder to do when holding the right way up - it seems that the bottom end needs to have the motion rather than the top end.
'Shake to Save' is sweet, however, it was inconsistent for me. I'm not sure if there is a particular shaking orientation that works best (it is hard to tell in your video). When it worked it was quick and easy.
At about medium sensitivity the average light sensor reading is around 14 when sitting on my desk on a cloudy day. If I set it on a chair closer to the window I get an average of around 25.
I am using ChangeScreen - a g-sensor orientation flipper: http://forum.xda-developers.com/showthread.php?t=468488
I've set an exception for 'gesture' but it hasn't seemed to helped (well, it does prevent the Gestures app from changing orientation when I tilt/shake the phone).