I had two pedigree cats and the last thing I would want them to do is a a stinky in the cabin. I flew PPL and had the family dog cut cheese admittedly in a 172 but hoo lee chk watering eyes.
"3. It must be a two-way system that can be activated by the pilot.....". The whole issue is from navigational waypoints taken, altitude changes, turns indicating use of AP it is clear that MH370 was unlawful interference, high probability the Pilot(s). Live streaming is data extensive and just check Flightaware with thousands of those dots airborne all the satellites on streaming overload. The DFDR's and other systems are hard wired. So a similar system linked with the initial flight plan that has a big continuous broadcast spazy if the aircraft goes off course or off secondary radar.
From another point of view instead of having long videos about patting your back on Antarctic research and climate change stuff - what happened to a couple of local celebs dong a short sweet safety video so I can go back to my movie. If you insist on long videos on climate stuff how about investment in more efficient aircraft and biofuels, you know the biggest expense in aircraft operating...... fuel.