This is your one-stop-shop video converter hands down. In the terms of service, it also says: “You shall not download any content unless you see a ‘download’ or similar link displayed by YouTube on the Service for that Content.” So whenever you see an indication of a specially prepared download link, you are able to do that however if it is artist material then it should really only be streamed. However, you can download some video clips outside of the above categories. Make sure you read all the terms of legality in the description of YouTube videos as YouTube doesn’t allow download of all videos.