10/40/70 is an approach to film studies developed by Nicholas Rombes in which one is forced to analyze a film through frame grabs taken at three specific times. In his own words, “select three different, arbitrary time codes (in this case the 10 minute, 40 minute, and 70 minute mark), freeze the frames, and use that as the guide to writing about the film. He explains this as “Constraint as a form of freedom.” (link).
This inspired a number of similar such approaches to writing on film. Dan North over on his blog, added to Rombes’ original idea the approach of using a random number generator to generate the timecode for the frame grabs. He explains his approach in this post. And the random number generator he mentions is here.
Rombes himself has a series of such film studies online here.