While I cannot provide a workaround off the top of my head, I may be able to shine some light onto the issue at hand.
It seems, based on your description, that the Security PC program displays the live video display using a 'video overlay'; for performance reasons. Similar to how WMP for example, will show DVD and other video content as a 'video overlay' (and should also
just show a blank box if viewed over Live Mesh Remote Desktop) to improve performance.
Content that is displayed using the overlay, is most likely not being 'fed' through the Live Mesh Remote Desktop capture, and without getting too technical, the Remote Desktop capture is not 'low/high enough' in the layers of the graphical display mechanism,
to capture this 'overlay' content.
As for a solution, try look for an option in the Security PC program to 'disable overlays' or 'disable performance enhancements'. Otherwise, unfortunately it is just a limitation of the Remote Desktop driver and most likely won't be implemented
for performance reasons.
ShadowXVII | http://www.shadowsplace.net