Tip: you may surface all video in your current view by using the Refine filter.
The file name and format is always displayed at the library thumbnail level, and in addition here a video icon.
Click the file in question to enter the Details view and play the video. This preview is an HTML5 render of your video file so much faster to load (and view) than the original video file. When you download the video file you are downloading the orignal.