Be sure to turn your phone or tablet SIDEWAYS (landscape) when you are shooting your video. Videos displayed on Mitzvites (or YouTube, Vimeo or any other site for that matter) are designed to be displayed in the widescreen format to maximize the amount of space your subject occupies on the screen. If you hold your phone or tablet vertically, there will be black bars displayed on the left and right side of your video and your subject will not be featured as prominently as they would in landscape mode.