In an earlier post I questioned how I could record from my iPad because my Mac Mini struggles to run the IOS emulator and Camtasia at the same time. Google is full of ideas from building frameworks which holds a camera steady above your iPad and actually recording the screen of the physical device, to hardware boxes which take a HDMI input and convert it so that it can be played on your computer screen. All of these are pretty expensive and take substantial effort. There is a simple answer. Use Reflection App.
Reflection App seems to work by pretending its an Apple TV. In the same way that you mirror your iPad display to render on the Apple TV, your Mac will now also appear in the list and your iPad display can be sent to it. I'm not sure how 'legal' this is under Apples terms and conditions but it works well and suits my needs. The free version allows you to record up to 10 minutes of video which will meet the needs of most people wanting to record demo's, but for $14.99 you can have the full version with unlimited recording.
On a side note, the same company have a product called Air Parrot which allows you stream your Mac desktop to an Apple TV. Mountain Lion has this functionality but if you have an older Mac (mid 2011 build for Mac Mini's) Apples solution won't work. Air Parrot will work and again costs $14.99.