In my previous post I described my unsuccessful tries on getting simultaneous front and back camera access on a Galaxy S5. I just got a new HTC One M8 and was surprised that it also had a dual camera app (just like the S5) so I tried my code again.
It turned out that it actually works on the HTC device see video below.
The code which relies on OpenCV 2.4.9 can be found here: http://goo.gl/9aBgQI
Excursions into Augmented Reality and Mobile HCI 