How to Add an Overlay OBS Studio In OBS, pick or create a scene. Sources → → Media Source → select overlay video. Check Loop. Uncheck Restart when source becomes active. Layer it right (below camera/alerts/gameplay) and lock. Set canvas to 1920×1080. Streamlabs Desktop Themes → My Overlays → Import → pick the JSON/scene file. Tweak sources if needed and save as new collection. Add Alerts StreamElements Overlays → Create Blank → add AlertBox. Upload alert video sound. Set duration and volume. Sav