Apple might think so! I had a popular YouTube downloader app for Mac OS and I spent a lot of time on a port for iOS, but it was rejected from the app store back

Apple might think so! I had a popular YouTube downloader app for Mac OS and I spent a lot of time on a port for iOS, but it was rejected from the app store back in 2010. The app reviewer did call me on the phone to tell me -- in fact, she called twice, once to tell me that my app was going into an extended review, and then a few weeks later she called to tell me that my app had been rejected. When I asked what the reason was, she told me to check the review guidelines ("check them again now" she said) and lo and behold, they had added a new guideline about downloading media without explicit IP rights. Moving the goalposts, one app at a time!