Eventually you should see the name of your PC appear (and probably your Wi-Fi router as well). Tap your PC name, and when prompted, enter your regular Windows username and password. I wouldn't let the app remember my password, but it's your choice. There is a way to ask Windows not to prompt for a password, but in my experience this feature isn't as reliable as just typing in your credentials.
Once you've logged in, you'll see a bunch of folders from your PC. Ignore everything but the Movie Night folder you intended to share. Tap it and everything contained in that folder should be available to you.
Now you can choose to either stream the movie over your home network or download it straight to your device.
Enjoy your in-network remote access, straight from your couch--but remember this feature only works when your PC is switched on and awake.
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