viki.com won't work properly with apple tv

my wife loves watching foreign movies on her iphone using viki.com. got her an apple tv so she can watch in bedroom tv, hooked apple tv and it works fine. she can play youtube from her iphone and connect to apple tv.

only problem, i can't make viki.com app work properly. i hear sound but, no video. i don't see the icon where you can switch to apple tv, to hear the sound i had to go to music and switch to apple tv from there. their website says app can connect to apple tv

any suggestions? already deleted app and loaded it again....