On the copyright front, as long as you're downloading a video for your own personal offline use, you're probably okay. But when the topic of downloading YouTube videos comes up, there's a side subject that must be broached: Is it legal? That said, sometimes, you really want or need to have one of those videos on your own computer or phone. And that's hardly the most astounding statistic about the site, which has been the go-to destination for uploading and watching video since 2005. There are billions of hours of video on YouTube. How to Set Up Two-Factor Authentication.How to Record the Screen on Your Windows PC or Mac.How to Convert YouTube Videos to MP3 Files.How to Save Money on Your Cell Phone Bill.