Yes- you are doing it WRONG!!! I beg you to please turn your smartphone horizontally while recording video. I know it looks normal when you watch it back on your phone but I assume you plan on sharing with others not looking at your phone (like Facebook, YouTube, Etc).
The following helps illustrate the issue and my frustration. Please WATCH and LEARN!
Vertical Video Syndrome – A PSA
Remember Vertical Videos Are BAD!