Using technology from these internet giants, thousands of football fans were able to watch long segments of many contests free of charge during the league's Week 13 schedule of games last Thursday and Sunday.
Dozens of these video streams, pirated from CBS and NBC broadcasts, featured ads from well-known national brands interspersed with game action.
This online activity comes as the league struggles with declining ratings that have been blamed variously on player protests during the national anthem and revelations about former players suffering from a brain disease caused by concussions.
Yet this illegal distribution of NFL content may also be crimping the league's viewer numbers.
The NFL strictly controls television and online video rights to its games. In particular, games played by teams that are not in a local TV market are often not televised except on DirecTV, and only for subscribers who pay extra for a package called "Sunday Ticket." That package starts at $55 per month.
If pirated versions of these games are available online users might ignore the DirecTV package, or skip locally televised games that they might otherwise watch. It also means that advertisers are reaching audience members that they did not pay for.
Facebook reportedly is prepared to spend more than $1 billion for the rights to future sports content, but as of now Amazon is the only large technology company with a streaming deal for football. It paid $50 million for the rights to stream 10 Thursday Night Football games this year.