I had the same question James! It’s an interesting debate and it can be hard to find what both YouTube and Amazon’s positions are. I’ve done some extensive research to get down to the bottom of this, and (in my opinion) it’s perfectly fine. I looked into stories where peoples accounts were suspended, but I never saw that affiliate links were the reason. I encourage you to do your own research on the matter. You might find this article helpful: http://blog.georiot.com/2014/10/15/using-affiliate-links-in-youtube-best-practices/ (full disclosure, I work there)

thanks 🙂