Export video of tracked surfaces

[papr]

There has been the feature request to be able to export the video of tracked surface content. To clarify, the video would contain the same content as the surface debug windows, including the gaze that has been mapped onto the surface.

[phauly]

It would be great to be able to have the option to export also the heatmap (if any) as an additional layer, i.e. the video of the tracked surface with the heatmap over it.