Are you using composite video rather than HDMI? If that's the case, obviously the app does not support it (and yes, you can set the 2710 (or 3710 for that matter) to 720 or even 1080p in composite mode, though obviously apps will only stream in 480i).
To tell the truth. (and I prefer not to judge other people's choice of apps, though there are some obvious apps that almost no one can resist trashing), the app in question is not worth it. Other apps (youtube for one...) have the same content.
Charter Spectrum 60; d-link dual band router
Roku 4210, 3710; Xbox One, 360; Samsung BD player
Samsung tablet; Windows Vista laptop; LG phone
Toshiba DVD-R; Sony AVR; Panasonic AR
1080p and 720p TVs