Summary: We don’t know.
In October 1997 Jakob Nielsen published an article that summarised his research into how web users read text online. His title/question “How Users Read on the Web” was quickly answered in a two-word summary “They don’t”. Nielsen then went on to outline his findings, demonstrating how people skim through web pages, rather than reading them fully.
Similar users studies have not yet been carried out with material from sound and video archives that is disseminated online. The results is that we know very little about how scholars use audio and video resources stored in digital formats. When trying to develop a sound archive of poetry recordings Murray and Wiercinski (2014) found that they could not do so based on researcher behaviour; they were “challenged by limited knowledge of how scholars of any kind conduct research that relies on listening instead of reading”.
The same is true for oral histories, particularly those that are not associated with texts (i.e. have not been transcribed):
“But little is known about how educators, makers of documentaries, students of non-material culture, historians, and others use video or audio materials that do not have transcripts. How do users search such materials? On what basis do they make relevance judgements? What metadata do they need?” (Gustman et al 2002).
The reason we know so little is because people using oral history archives has historically accessed oral history material through the transcript, despite the recent emphasis on the primacy of the recorded material (see a discussion at Transcription and Oral History). Klemmer et al. (2003) noted this incongruity and concluded that it resulted from the fact that books were more usable than audio. In the world of widespread multi-media websites, this observation may no longer be relevant (or it is at least likely that the widespread preference for books and paper-based text is waning). Yet the fact remains that we still know relatively little about how people use oral history material when it is put online in audio and video formats, although we hope that they do access it.
Gustman, S., Soergel, D., Oard, D., Byrne, W., Picheny, M., Ramabhadran, B., & Greenberg, D. (2002, July). Supporting access to large digital oral history archives. In Proceedings of the 2nd ACM/IEEE-CS joint conference on Digital libraries(pp. 18-27). ACM. http://svr-www.eng.cam.ac.uk/~wjb31/ppubs/jcdl02malach.pdf
Klemmer, S. R., Graham, J., Wolff, G. J., & Landay, J. A. (2003, April). Books with voices: paper transcripts as a physical interface to oral histories. In Proceedings of the SIGCHI conference on Human factors in computing systems(pp. 89-96). ACM. http://dl.acm.org/citation.cfm?id=642628
Murray, A. and Wiercinski, J. (2014) A design methodology for web-based sound archives. Digital Humanities Quarterly Vol. 8.2. http://www.digitalhumanities.org/dhq/vol/8/2/000173/000173.html