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This paper deals with free-surface flows in a geometrically simple apparatus consisting of a rotating cylindrical drum with horizontal axis and a fixed internal plate. The drum is partially filled with a very viscous, optically transparent liquid and is otherwise filled with air as a passive phase. Due to the rotation some liquid mass is dragged upwards along the moving wall, scraped off by the fixed plate and forced to fall back into the liquid pool due to gravity. The resulting flow and the shape of the phase interface are visualised within a plane perpendicular to the cylinders axis. Different flow phenomena are detected, depending on the volumetric filling degree F and on the dimensionless parameter = g R/(ν ), which quantifies the relative influence of gravitational and viscous forces. Extended lubrication theories are used in order to model the shape of the phase interphase and to predict the conditions under which inner film flows may be expected. Some findings are validated by results of a more sophisticated numerical free-surface-flow simulation.