Large-scale multimodal communication research increasingly depends on computational methods capable of extracting reliable gesture annotations from video data. Yet it remains unclear to what extent automatically generated annotations can support the linguistic investigation of naturally occurring co-speech gesture and where expert interpretation remains indispensable. This paper presents a framework for the automatic analysis and annotation of co-speech gesture in media corpora, developed to support multimodal communication research at scale. We build our framework on top of the existing computer vision frameworks for keypoint extraction and active speaker detection, with post-processing steps carefully designed to mitigate noisy output. Building on the processed keypoint trajectories, we implement a configurable rule-based annotation system developed through close collaboration between computer vision researchers and linguists. We demonstrate the usefulness of the framework through a case study investigating vertical hand movement accompanying English expressions of future and past, examining which aspects of this gestural pattern can be captured through automatic annotation and which require expert multimodal interpretation. We find that at corpus scale, greater mean amplitude and higher mean peak velocity converge in *will*-future, suggesting greater kinematic prominence in the multimodal expression of futurity. More broadly, the case study demonstrates how computational pipelines can support, rather than replace, human analysis by enabling multimodal hypotheses to be investigated on datasets that would be impractical to analyse manually.