body: If a developer creates Android and IOS applications that use YouTube API, what limits are legally applicable?. Suppose the applications will get videos from YouTube, then will manipulate these videos, accelerating, slowing down, playing only certain interval, etc.
  
  
  1. If the apps have ads, is there any copyright problem with the video owners or YouTube company.
  2. Is it a copyright violation or other legal problem to excerpt the videos on YouTube? For example, the apps play only the first minute of the videos? Can the app add extra sounds on these videos?
  3. Is it allowed to play videos on the background? I mean, can the app play only audios of the videos?
  4. Is there any legal way of playing the YouTube videos without YouTube ads in such apps?
  
  
  
title: Manipulating YouTube videos in mobile application