Can't move videos to Camera Roll.

I'm begging you for help. I haven't found the answer to my problem anywhere. I wanted to move the video files recorded on my android phone for editing in iMovie. I transferred 46 mp4 files via iTunes to the device. And here's the problem. They're stuck in the Files in "On my iPad". I can easily play them, watch them, but I can't move them to the camera roll, so iMovie or any other video editing software can't find any of these files 😞. How to move them all? I already used 3u tools - it doesn't work, it doesn't even want to convert files. When you try to move with the Documents application, you see PHPPhotosDomain error - 1.