Import your newly downloaded .mp4 overlay and your action camera footage into your video editor (Premiere Pro, After Effects, DaVinci Resolve, Final Cut, etc). The overlay has a solid background — set its blend mode to “Screen” (or “Lighten”) so the dark background drops out and only the bright speed readout shows over your footage.

Place the Verdant Speed overlay on the track above your action camera footage. Stretch (or time-remap) the Verdant Speed video so its start and end perfectly align with the beginning and end of the GPX measured portion of your action camera video. You can drag and position it in any corner of your frame!