Audiovisual recordings of lectures are available to many students in all disciplines. The use of lecture recordings has been studied extensively, but it is still not clear how, or how much, they are actually used. Previous analysis of their use has been based on either survey data or computer logs of access. In the latter case, measurements of actual use have usually been based on counts of the number of times recordings have been accessed. This does not distinguish those that happen accidentally ('hits'), from those that might permit learning ('views'). This distinction is essential to the meaningful analysis of the log of the actual use of recorded lectures. Using the access logs of undergraduate science students, we show that the distribution of the durations of the access of recordings of scheduled lectures has two distinct components. The most rapid of these is complete within three minutes and we infer that it reflects the behaviour of students searching among recordings. This inference is based on a comparison of these distributions with those of (i) recordings made automatically during a non-teaching period and (ii) individual users. This is also consistent with the pattern of usage by students searching for a specific recording.