NOTICE FOR IPHONE 4 USERS
Unfortunately, due to some technical limitations we are unable to support the Video Slideshow upgrade in Collect for iPhone 4 users. Video generation works as expected on all other devices except the iPhone 4 so if you are getting a new device soon you will still be able to use this feature.
Users who have purchased the upgrade & have an iPhone 4 device are able to get a refund for their purchase via Apple. A good set of instructions on how to do this can be found on this site: http://www.imore.com/how-request-refund-itunes-or-app-store-purchase.
Thanks for your understanding if you've been affected by this issue.