One of the major essays of Chris Markerwhich automatically makes this one of the key works of our timethis remarkable 1993 video is provisionally about his friend and mentor, the late Soviet filmmaker Alexander Medvedkin (1900-’89), in the form of six video letters sent to him posthumously. More profoundly, this is about the history of Soviet cinema and the Soviet Union itself, about what it meant to be a communist, about what these things mean now. In the process of redefining these issues, Marker produces a guarded self-portrait and autocritique, implicitly asking himself what his own leftism has meant and continues to mean. Eloquent and mordantly witty in its poetic writing, beautiful and often painterly in its images, this is as moving and as provocative in many respects as Marker’s Sans soleil (1982). Not to be missed. 116 min. (JR)