If you mean to make a movie of the iPad in action (vs a screenshot) - then I'm afraid there's no real option for a stock iPad.
If you jail break, you can buy and install the tweak "Display Recorder" ($4.99, USD) - that does make a video of the iPad in operation.
There was an an app in the App Store that did this - but it was expensive and has terrible reviews (if it even still exists; I don't even remember the name of it).
Sorry, but it's not really possible on a stock iPad.
Marilyn