Capturing a real-time screencast of apps and games running on your iPhone, iPod touch or iPad used to require juggling with various devices/cables.
As our own Jeff Benjamin would explain, a typical solution would involve using a pro camcorder to physically record the screen of an iOS device and taking advantage of one of Lightning digital A/V adapters to feed live video from your iOS device to a computer or a specialized video capture device.
Starting this Fall, iOS 8 and OS X Yosemite will greatly simplify the process by allowing you to capture a screencast by connecting an iPhone, iPod touch or iPad to a computer using a Lightning cable, no A/V adapters or HDMI capture cards needed whatsoever...