The FAA has interpreted the rules to mean that the operator must have a line-of-sight view of the model aircraft at all times, and that FPV does not qualify.
Based on the plain language of the statute, the FAA interprets this requirement to mean that: (1) the aircraft must be visible at all times to the operator; (2) that the operator must use his or her own natural vision (which includes vision corrected by standard eyeglasses or contact lenses) to observe the aircraft; and (3) people other than the operator may not be used in lieu of the operator for maintaining visual line of sight.
But also note that this does not apply if:
...the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;
The above is from the linked NPRM released in June 2014. The latest NPRM from February 2015 has the same requirements.