The answer is somewhat convoluted but here goes.
1st and foremost on the original IPad you must be in "auto" or "Hi res" mode . The app always defaults to "SQ" or standard quality mode. There are several soft keys at the top of the app screen. Select the "3 parallel and horizontal bars" one to access the video quality and aspect ratio buttons on the bottom of the app screen. This is the left most symbol.
If you haven't set the video mode to Hi or auto quality modes you will only get audio out using AirPlay . Next select the aspect ratio button and the airplay symbol will appear. Select airplay to you preferred device and you will then, wifi signal strength permitting, be able to view your slingbox signal on you TV but only in 4:3 ratio mode. Hope this works for you. It isn't perfect but it's all we got so far.