Both. Videos are compressed prior to upload, and you can choose to upload from any connection type.
If you are out and about and prefer to upload over wifi:
Please record the answers to your survey questions using your phones video camera as normal i.e. without using the 'record now' option in the app (Android) or Verbate in your web browser (iOS).
Head back into Verbate in your web browser, click on that question and select 'Photo Library' and upload your video from your gallery.
Reopen the Verbate app, click on the question and select 'Upload Exisiting' from the pop-up menu. Choose the right video from your gallery and the app will do the rest!