Net revenue is gross (total) revenue minus returns and any other negative revenue. (Expenses have nothing to do with Net Revenue. Net Revenue is NOT the same as profit.)

Just because net revenue is down, does not mean that the market didn't already account for this change. The real thing to look at is EPS and expectations. Additionally, after hours should not be used as any indicator since the volume is basically insignificant.

looks like the stock tanked initially but has recovered since.

Refer to chart: http://www.marketwatch.com/investing/stock/amzn

Agreed, looks like techcrunch fishing for a headline.

Net income did tank 96%. Net income refers to profits, not revenues.

Looking at the chart near the end, it shows the little sliver of a bar that's about 4% the size of the bar that comes before it.