A freeform application is ideal. Getting a Video seems extremely inefficient, seeing as if English isn't one's prime language, or somebody has a heavy accent,(Tully: Moataz's Accent Is Fucking Fabulous.) it would be hard to evaluate properly. Text is easier to understand, and in overall allows us to understand and check ups and downs without need to re-watch a 3-5 minute video multiple times. So to answer your question, a Text based app preferably.