Download an app called Video Downloader Professional. Then chose a youtube video that you want to download to your computer and go to it. In your top right corner, there will be a movie reel that will turn into a green arrow pointing down. Click the arrow then click where it says "here" in red. It will take the video to a different site. Play the movie, click the arrow at the top right again, then click the download at the bottom that is green and says mp4. It will download to the download files on your computer. I have never had trouble with this so have fun!