Make sure you have your cloud drive's app installed on your iOS device.
Open Switcher and select the hamburger menu in the top left corner.
Tap My Recordings.
Select the video you'd like to export to your cloud drive
Tap the share icon in the bottom middle of the screen.
Tap "Open In..."
Scroll to the right until you find your cloud drive app
Tap your cloud drive app and select the right account if needed. (For Dropbox you'll need to select the destination folder and person you're sending it to. I usually just put my own email here.)
Tap upload (Post for Dropbox) in the top right corner.
Leave your iOS device open until your file is fully uploaded to the cloud drive.
That's it! Once uploaded you'll be able to access your video file from Google Drive or Dropbox.