There are 2 common ways to capture a video signal from an iPad.
Software like Airserver or Reflector offer ways to send the output of an iPad directly to your laptop. It´s a very good solution to capture up to 720p resolution videos if you use a 5 GHz network and have a rather new ipad model with a Wi-Fi (802.11a/b/g/n/ac). It also allows to use the Tagtool videosignal in most VJ software like Modul8 or Resolume via Syphon.
If you want high resolution videos i would recommend using any capture device (e.g.: Blackmagic or Vision Dimension) that is directly connected with your iPad. This allows recording of Tagtool multiplayer sessions, because you are not using bandwidth for video streaming and you can capture the best quality you can get out of an iPad up to 1080p. Also any VJ software will see the device as an input device with low latency for live-visuals.