accelerometer: is very low bandwidth (think ~10-1000 measurements per second). The noise is ~100μg/√Hz - with 12 bits samples I'm not sure you'll pick up HDD vibrations (but rather easy to test).
Someone should lend the people researching this an oscilloscope.
No, not QR codes since it would require the webcam capturing the screen directly. The screen may be used as a light source for the transmission and the webcam can capture the light reflecting from the walls...
accelerometer: is very low bandwidth (think ~10-1000 measurements per second). The noise is ~100μg/√Hz - with 12 bits samples I'm not sure you'll pick up HDD vibrations (but rather easy to test).
Someone should lend the people researching this an oscilloscope.