“Forgotten Transports” stand out from the multitude of Holocaust documentaries because its director, Lukas Pribyl, did more than track down survivors or burrow through film archives and deportation records. Over 10 years and visits to 30 countries, he hunted down photographs of SS camp commanders and snapshots taken by local residents and workers who might have encountered inmates, sometimes trading bottles of vodka for the artifacts. The impression conveyed is that a photographer was along for the nightmare ride of the Czech Jews. Together the films trace the experiences of 76 of the 270 survivors among the thousands of Czech Jews deported, not to the familiar Theresienstadt ghetto or to Auschwitz, but to less-well-known camps like Jagala and Kaiserwald. Mr. Pribyl chose that approach because his grandfather was sent to an obscure camp.