For example, Video content of Android Java Masterclass - Become an App Developer (ref:https://www.udemy.com/master-android-7-nougat-java-app-development-step-by-step/ ) are not fit for 5.5-inch mobile phone, content, which had done by lecturer, only be considered for audience will watch them by at-least 13-inch screen. Not mobile first and audience context-thinking. Terrible mobile-device experience. I will preview every content before I want to buy them on udemy.com .