We have multiple reports of our h.264 video playing audio-only in IE11 on Windows 7. The video screen stays black. I can reproduce the problem.
Here is an example video that exhibits the problem. Downloading it and playing it in Windows Media Player also reproduces the problem.
Visiting https://www.youtube.com/html5 indicates that html5 and h.264 are supported by my Windows 7 test machine, so my thought is that the problem has to do with the particular settings I used to export the video from Premiere Pro (current CC version for Mac).
Has anyone run into this before? Are there known "safe" settings for exporting h.264 from Premiere so that it will play back properly on Windows 7?