Background Understanding and addressing the unmet mental health needs burden in the Northern Province of Sri Lanka is the subject of the COMGAP-S two-phase study. Phase Two involves the implementation of the World Health Organization’s mental health Gap Action Programme (mhGAP) in primary healthcare settings. As part of the contextual adaptation of mhGAP, eleven of the videos provided in the mhGAP training package have been re-filmed by a local team. We investigated the challenges, barriers and good practices of this adaptation effort from the point of view of team participants. Methods Twelve persons from the adaptation team, including students of medicine and drama, doctors, drama lecturers and professionals, consented to in-depth individual interviews following an open-ended topic guide with a member of the COMGAP-S study team. Interviews were recorded, transcribed, translated as necessary, and subjected to thematic analysis. Results The majority of participants perceived the process positively and had pride in their involvement. Expectations, opportunities, and exposure were discussed as stemming from the video production. The main challenges derived from the analysis were lack of discussion around budgeting, logistical difficulties, struggles with team cooperation, and creative differences. Issues around exact translation into the local Tamil dialect and modelling around mental health were emphasised by the majority of participants. Potential uses for the videos were identified beyond the current study and recommendations included setting out clear guidance around available funding and role allocation, and increasing the flexibility in adapting the material. Conclusions This study illustrated details of the adaptation of existing video materials to facilitate locally-based training for non-specialists on mhGAP curricula. With this, we have added to the knowledge base on conducting cultural and language adaptations and our findings indicate participants felt adapting the mhGAP films to local context was vital to ensuring training materials were culturally appropriate and valid. Trial registration This project was nested within the larger COMGAP-S clinical trial. Ethics approval was granted from the Ethics Review Committee, Faculty of Medicine, University of Jaffna (J/ERC/17/81/NDR/0170) and the Faculty Research Ethics Panel, Faculty of Medical Science, Anglia Ruskin University (SC/jc/FMSFREP/16/17076). The project is registered with the Sri Lankan Clinical Trial Registry (SLCTR/2018/008) and listed on the ISRCTN registry (trial ID ISRCTN62598070 ).