You don't just have to use the app. You can watch via a web browser. Connect the device (phone, tablet, laptop, desktop) to a TV via HDMI. Select that device from the input list on the TV. The TV then becomes a monitor for the connected device.
Sign in to your account from the MSG web page, select the feed like you would any other video and expand the view so it takes over the screen. It'll be just like watching any other feed on TV.