As a general rule, clothing designs cannot be copyrighted, but particular designs that are subcomponents of a design (e.g. a painting on the back of a T-shirt) could be copyrighted.
The image of the clothing brand is a trademark. Contrary to common belief, it is not infringing to have an image with a trademark that you don't own on it. What is infringing is using a trademark to sell merchandise of the type that the trademark applies to without a license from the owner of the trademark.
If you are using the app images to sell "Lovis" jeans, and the "Lovis" trademark appears and is used without permission (and the goods are not clearly designated as being sold "used" since there is a version of the first sale doctrine that applies to trademarked good), then you are infringing. But, if you are using your app to sell, for example, hotel accommodations or ride sharing services, and the models happen to be wearing designer clothes with visible designer brands, you are not really infringing although a disclaimer stating that the companies owning the displayed brands do not endorse your product or the products being sold would be prudent.
Of course, if you edit the video to obscure the brands, there is no colorable way that someone could prevail in suing you for trademark infringement, and usually no one would even attempt to do so only to fail, so that would be the safer course of action.