Some believe the players' claims could be worth $1 billion or more if they move forward in court. The cases involve the deaths of players,
Fjallraven Kanken Italia, medical care of players with disabling dementia, and lifelong medical monitoring for those who are now symptom-free.
The NFL on Friday denied a New York Times report that it had pressured ESPN to drop out of the project with "Frontline." The sports network has a lucrative contract to carry league games on "Monday Night Football."