The poll shows Clinton +9 currently.
The poll is conducted online, but if you're a smart person, you've installed an ad-blocker, which means you won't be polled. Hence the poll skews stupid right out of the gate.
The poll is of registered voters, including lots of motor-voters, not of likely voters, and the most likely to vote are 60 years of age and over. In 2012 70% of them turned out, but this poll this week of 15,179 includes just 657 people over 65, or 4.3% of the total. The poll therefore can't be said to reflect the opinion of those most likely to vote.
Here's what it does reflect. In 2012 turnout of people 18-44 averaged about 47%, yet this poll is 46% of that demographic, or 6,920 people, only 3,252 of which are likely to show up in November 2016.
You can make a poll say anything you want by playing games like this.
The NBC/SM poll is trying to shape opinion, not measure it.