All sales are estimated. NPD publish estimates too, they just use a larger sample size. It is impossible to get the exact sales figures off every single retailer in the world each week so sales trackers have to estimate sales based on the data they're able to gather.
Let it through, it's a good April Fool!
If this is backwards compatible I'll get it!
It's a British site so it's in pounds not dollars. It clearly says "Total: £1423"
The blog post you sourced has been removed so presumably it's fake.