After calibration the sensor should read a steady 20.8-20.9 when resting in free air. If you read the LM-2 manual (it installs with Logworks3, sift your Start menu), reading richer than that even by a tenth or so indicates a sensor that is either going bad or ready to be thrown away.
I've had my LM-2 read supa-lean in bold before, usually during decels or when breaking up under load, and other odd transitories where I figured the sensor's temperature had been compromised (temperature has to be precisely controlled or it's output is not accurate). I'm ASSuming you sprayed the towel in your video with butane or carb cleaner or something? The way the wideband behaves is not anything I'm used to, and sensor response seems to be really slow. I hate to say it, but try another sensor. You're going to be trying another sensor a lot as long as you run shelf widebands - the sensors are a VW/Bosch part, hope you weren't expecting quality.
I have no experience with the APU1. I'm pretty sure Tunerpro supports it, try to flash your Crome .bins with it and see if that helps you troubleshoot.