A soft page flip allows the client to see the flipbook feature as a closer representation of what a press book might look like. The soft page flip shows where the crease will be in the spread. This feature is geared towards press books, but will provide an accurate idea of where the seam in the center of your album will be.
Check 'Soft Page Flip' in the Flipbook Options tab to enable a soft page turn that simulates the flexibility of a press book page. Click Next to continue.