It is legal to use online video downloaders, as long as a user is downloading and sharing files that are licensed or in the public domain, according to New Media Rights. Illegality arises when the technology is used to download unlicensed material.
It is also legal to stream licensed videos and watch them for personal use, states New Media Rights. The person who has downloaded the unlicensed material and posted the video has broken the law, but the person watching it as a streaming file, as long as it is for strictly personal use, has not broken any law. However, even if it is unintentional, the moment that any part of the unlicensed material is downloaded into an unlicensed hard drive, even if such material is never shared, the owner of the hard drive has broken the law. The owner breaks another part of the copyright law if the material is shared through a file sharing site. This is known in legal terms as unlicensed distribution and in more colloquial terms as piracy.
Many online streaming sites avoid legal consequences because they are not the ones distributing the content, but acting merely as a search engines and host, reports Business Insider. The unlicensed material may be copied by the user from a secondary site into the user's hard drive.