Probably not. And Neilsen may soon be including some Walmart (maybe even has started too). The reason they weren't were Walmart's decision to not supply the info. But Walmart is starting to use a Nielson designed system. Some numbers from Walmart are again flowing to Nielson, but apparently not yet the video disc info.
Walmart give numbers that will be the day. They know what people want that's why they are #1, and sell 40% of this country's DVD sales.