Flipgrid is an app, and website that allows students to record video responses. The videos are usually reflections, or responses to a specific topic/prompt asked by the teacher.
A good thing to note is that student responses on Flipgrid are public to the class, so all students in the class will be able to see each other's responses. You have the ability to customize moderation (so that videos must be approved by you before they are posted), as well as the option for students to engage with each other's videos. So, this is not the best platform to use if you want video responses to be private (between you & the student). It is possible to leave private feedback on student videos.