How can I use my Samsung S5 rear facing camera to video chat?

[AC Question]

Samsung S5 rear facing camera / video chat

I've got a Samsung S5, and whenever I used chat sites like Omegle or Chatroulette, it defaults to the front facing camera. This is the same for certain web meeting programs as well. How can I get it to use the rear facing camera? It gives me the option on google hangouts, and Skype.