I haven't tried - can you watch pro sprots live, online for no additional charge with no need to prove you have a cable subscription and no ads? I googled around and found something called NFL Game Rewind but it looks like a subscription.
I'm sure sports like everything else will be sold online if it isn't already. But sports fans have proven to cable co's that they are willing to pay up the wazoo for live sports, which keeps the price high so Netflix won't be able to afford to add live sports and keep their cheap prices.
Chart of wholesale cable costs.
Notice how out of whack sports channels are compared woth everything else. The sports biz isn't going to undercut their ability to command those prices by giving away their golden goose for free.
As TV enters its death spiral, live events will be the last thing it holds onto, since ads can still be effective for something that loses value when its DVRed.