keep in mind that walmart isn't making the discs at the store
short explanation:
in the end, walmart only makes 3% profit from the stuff they sale
assuming that hold true for everything they sell, then they are only making $0.69 from that $23 blu ray disc.
but it doesn't. some stuff has a greater profit percentage, some stuff has less. 3% is just the average profit.
long explanation: (i was bored

)
there are plenty of other costs to factor in.
besides the licensing/royalty fees that have to be paid, theres also transport of those discs from the factories to the manufacturers warehouses, then to distribution centers, then to the walmart distribution centers, then to the the stores. with each stop adding a few dollars to the cost.
so the cost breaks down to paying for all the various markups, transport, and storage of those discs. in the end, i wouldn't be surprised if each walmart store only made a few dollars per disc sold, before store level expenses are even taken into account.
and...as for those store level expenses...
between 01/31/2006 and 01/31/2007, walmart:
made 348,650,000,000 in gross sales.
lost 264,152,000,000 to the cost of the product.
leaving only 80,840,000,000 in gross profits from sales
they then paid 65,530,000,000 in operating expenses (employees, stores, etc)
leaving them with 18,968,000,000 before taxes.
they then had to pay 6,365,000,000 in income tax on that.
plus then a few other smaller charges of less then 1bil
in the end, the 7131 stores worldwide made 11,284,000,000 in net profits in the year between 01/31/2006 and 01/31/2007.
only 3% of the money they made from sales.
and most of that remaining 11bil is owned by all the people who have stock in the company.
references/resources for the above:
financial statement:
http://moneycentral.msn.com/investor/invsub/results/statemnt.aspx?symbol=wmt
number of stores:
http://investor.walmartstores.com/phoenix.zhtml?c=112761&p=irol-irhome
comparitivly, microsoft only made 51 billion, and in the end after all expenses, had 14 billion.