Here's the 'how it works' video on smartphone accelerometers, you'll love the clever way a microscopic cantilevered beam of silicon is created in the heart of the accelerometer:
And, while we're here, here's Bill's take on how LCD displays work, albeit on a larger scale than smartphones (and note that many phones now use AMOLED tech, which is subtly different again).
Finally, here's a (slightly dated) look at the main constraints designers have to face in designing 'cellphones':
Well presented content throughout.
More videos like these on Bill's YouTube channel.