The use of video recordings as data in research studies in science education began in the 1970s. After almost thirty years, this use is widespread among researchers; video is included in regular research practice. However as any "new instrument", video has modified researchers' practice to the extent that the nature of information given to researchers is different from that of written data, direct observation and even audio recordings. In this chapter, our aim is mainly to give insight into the characteristics of video data and the complex nature of video. In part one we present specific characteristics, mainly the physical ones, then in part two we discuss to what extent one main characteristic of the video is its analogy with the recorded part of the situation in terms of events kept or transformed in the analyses, and in part three we present an actual research study.