Nathan
I have just tried your capx via cocoonjs launcher and can confirm it doesnt work for me either
you can look in the console of the app to see the error which you can pass on to Ludei
Its erroring on trying to open the path to the files folder, maybe you need to add a prefix on the uri path to help it point to the right location but searching the forums i havent found any info on what that might be
It definately works loading from live urls though as I just implemented this yesterday to include ads to our other games from within our new game, which strangely enough is also an educational childrens game