What is the ruling on benefiting from educational video files downloaded via a wireless receiver, knowing that some of them were downloaded before becoming aware of the impermissibility of using it, and others after that?

It is not permissible to use an internet connection without the permission of its owners, as this constitutes an infringement on the rights of others. You must immediately stop this forbidden act. As for the files and programs you have downloaded, there is no harm in benefiting from them, because the rights that burden your conscience are owed to the owners of the internet connection, and not to the files or programs themselves.