A mixed-media presentation should give every element a clear job. Photographs, words and moving images can support one another when they share an idea and an appropriate pace.
Choose the role of the photograph
Decide whether each still image introduces a setting, holds attention on a detail or closes a sequence. Avoid adding motion only because the format allows it. A still frame can create a useful pause between faster elements.
Check credits and permissions for every component and test the presentation without sound where relevant. The visual thread should remain understandable when a viewer encounters only part of the work.