Motion 3 includes a new version of the content asset named Fire Burst.mov. If you created a project in a previous version of Motion that included Fire Burst.mov, you may notice that the asset has changed. The asset that was named Fire Burst.mov in Motion 2 is now called Fire Burst 2.mov in Motion 3.
If you created a project in Motion 2 using the Fire Burst.mov asset, you can restore the original appearance by simply replacing Fire Burst.mov in your project in Motion 3, with the new Fire Burst 2.mov asset.