Created attachment 294340 [details]
Screenshot of problem page
I have an absolutely positioned container with 'transform: translateX(-50%) translateY(-50%)' and 'overflow: hidden' properties. Inside this container I have an absolutely positioned video and several absolutely positioned images. As you can see on the screenshot, 1 pixel of video is displayed to the right and to the bottom of the container, though overflowing part of the container content must be hidden.
Example is available at http://academy.spaceapp.ru/test.
Created attachment 294382 [details]
This seems more like a subpixel bug. Reduced test case attached.
Also it has nothing to do with video. It's two <img> and the on-top one doesn't fully cover the one underneath.