The zero-frequency spectral densities J(0)(0) data(1) for the liquid crystal p-(methoxybenzylidine)-p-n-butylaniline (MBBA) is quantitatively interpreted using a model that includes director fluctuations and rotational diffusion of symmetric rotors in a nematic phase. The contribution to J(0)(0) from director fluctuations has mainly a second-order component, whereas the first-order contribution to J(1)(omega) is suppressed in the megahertz region (Larmor frequencies are 15.3 and 46 MHz) due to the high-frequency cutoff, which is estimated to be around 3-10 MHz for MBBA. A global target approach is used in the analysis of all the available spectral densities. As a result, motional parameters and a molecular prefactor for director fluctuations are obtained in the nematic phase of MBBA.