I don't think payed replays are the best idea, they are borderline legal for starters. As far as I know, a picture/video is the property of its taker, just like a painting is the property of its painter. In this conditions, cashing in on replays is clearly copyright infringement. That means snapchat has to include a paragraph in the terms of service that the picture can be used by Snapchat in comercial purposes, meaning they get money from your photos, while you don't. If they ever get sued over it, those might be considered unfair contract terms and they might be forced to pay a % of the revenue from replays to the takers of pictures, so they are taking a bit of a risk here.
Yeah its kool...worked on my lg g4...thou we really need for windows 10 Mobile...iam sure microsoft may just purchase snapchat...if they dont support windows mobile...lol