None of the soldiers in the Civil War, or any other war, died for a flag, for a piece of cloth. They died to keep our country free, for our freedoms. All of our freedoms, including our First Amendment right to free speech. (There's a reason our forefathers made it the FIRST amendment). That includes protesting where you think it's necessary. That's what these players are doing. You may not like it, but that's too bad. You have the right not to like it. Their employer gave them permission to do this - not during the game, but before the game starts. 

And how many of you sit at home during the anthem, eating your wings and nachos, guzzling beer, wearing your Broncos hats? How many of you actually stop, stand up, remove your cap, swallow your food and booze, cover your heart with your right hand, and sing the anthem. I bet it's not a lot of you.