I think he was talking about angular resolution. EM wave arrives at different antennas at slightly different time. The phase difference allows for very high resolution of the direction the wave is coming from. [VLBI](https://en.m.wikipedia.org/wiki/Very-long-baseline_interfero...) effectively produces an antenna with an aperture the size of the Earth. To make it work one needs extremely accurate time synchronization and spatial location. In the interview he talked about continental drift of several millimeters per year. Those are the things they need to compensate for.