You may already know that if you place an animated GIF in your InDesign document and want to export it with in5 with the animation intact that the frame must fit to the content. Scaling the animated GIF works, but if the frame that contains the animated GIF crops the content, then in5 will interpret that to mean that you want a newly created cropped raster image.

But what do you do if you'd like an animated GIF to play through a custom shape? 

You can place the animated GIF, fit it to a rectangular frame, and then use a compound path to mask the parts of the animated GIF that you don't want to show. Here's how:

  1. Make a rectangle that completely covers the animated GIF and is filled with whatever color you want to mask portions of the animated GIF.

  2. Place your custom shape where you want it over this new rectangle.
  3. Select both the custom shape and the rectangle.

  4. Go to Object > Path > Make Compound Path.

  5. As long as the animated GIF is fit to its own frame, then it will play though the punched-out shape in the compound path that covers it when you export with in5.

If you don't yet have an in5 license, you can try this out with the demo version.