My guess is that each device implements the video buffer at bit differently. A Larger buffer allow the device to compensate if the network connection functuation. The device has a larger portion of the stream in its buffer and can continue playing the videoif the connection temporarilly degrades. The downside is that the initial video playback takes longs since the device must fill its larger buffer before starting playback.
Regading monthly payments to Verizon; yup same boat. I have TV, Phone and Internet, that with equipment costs me over $170 per month plus 4 smart phones on a wireless and data plan that runs me close to $250 per month. Up until the Netflix crap I was happy enough with Verizon that I wouldn't have considered changing providers. I am now so upset that I WILL CHANGE at the first possible opportunity. I've spent more money with Verizon over the past 15 years than I care to think about and the Netflix debacle is unforgivable.