You can use a GUI-based software to rotate multiple videos at once. Here, I am going to use this free software called XMedia Recode. It is a free video converter and editor software for Windows 10.
Learn a quick and simple way to rotate videos you have taken vertically using Apple's iMovie '09 or Quicktime Pro 7. Users should be aware that Quicktime Pro 7 is a $29.99 upgrade to Apple's Quicktime ...