WiFi Baby Monitor Hacked: How Hard is it?

Had a call from TV news asking how hard it is to hack a baby monitor. There is a story going around, which may have been recycled from last year:

1. This year: Stranger Hacks Into Baby Monitor and Screams at Child, Olivia B. Waxman, Time, April 28, 2014:
2. Last year: Baby monitor hacked, spies on Texas child, Chenda Ngak, CBS News, August 13, 2013, 6:22 PM:

I found some sensible advice about securing your router, changing the default password and the like in "Can my WiFi baby monitor be hacked by predators?",  Liz, Home Security, April 28, 2014. Anything more anyone can suggest?