"Video commentary" refers to expressing ideas, opinions, or explanations about a video or film, usually done through spoken words or written text while the video is playing. Full definition
We will be streaming our gameplay and video commentary on launch day. (nintendofuse.com)
Users can record video commentary while playing a game using their smartphone or tablet's front - facing camera or record clips of themselves playing to upload at a later time. (techtimes.com)
And if traditional comments at blogs are obsolete, could video commentary revive them? (legalblogwatch.typepad.com)