This is Basilio Martín Patino’s film Caudillo, and we do not understand why FalangeTV are the ones who have put it up. You can also see his Queridímos verdugos, where he interviews executioners and prisoners from the Franco era, and two hours’ worth of Civil War footage chosen and arranged by him.
Pío Baroja witnessed numerous executions, and an interesting Spanish professor wrote Verdugos y ejecutados en las novelas de Pío Baroja (Palma de Mallorca, 1966). In 1890, Baroja and Emilia Pardo Bazán both witnessed the last public execution in Madrid, of Higinia Balaguer. Da. Emilia wrote a crónica about it which was published in El Imparcial the next day.