Where are downloaded movies stored on my iPad?

Movies downloaded within specific apps such as the Youtube App, or Amazon Prime app, would be stored inside the App only. They would be nowhere else.

The Amazon Prime App has a Downloads tab at the bottom, and the Youtube app should have a Downloads section in the Librar tab.

You would need to delete them from inside each app to stop them from taking up space.

Files you download from a browser on the iPad should go to the Downloads folder. Do you use iCloud Drive? If you go to the Files folder, you should see a Downloads folder, and any other folders created. As far as the app is concerned, you would need to ask their support where they may be, but my guess is they are downloaded to the app.

If they have been dowloaded to the device, they will take up memory. They have got to be somewhere in the Files app when you download them. Although I can say that I've never tried to download a movie from a browser, or YouTube, so I cannot compare. I just tried to download a video from YouTube, and it appears as a link in my Files app.

Did you look in the Files app?

What were you using to download them? Safari, another browser, a particular app?

I know you said you don't use it, but did you look in the TV App?

You're welcome. Sorry I was unable to help.