Most of it can be done using InDesign, but you may use Acrobat for finishing touches.
There are two fundamental possibilities how that animation has been made.
a) If the document was shown in Fullscreen mode, there would have two pages, the first one with the first part of the sentence, and the second one with the added second part. For the second page, a Page Transition has been set, which runs when switching from the first page to the second one. This scenario is rather easy to implement in InDesign, and may only need Acrobat to properly configure the Fullscreen properties and the page transitions.
app.setTimeOut() (and its terminating method