Using ReplayMod 1.15.2-2.3.2 and rendering any video using the mp4 High Quality preset renders the video with an extremely high bit rate usually in the range of 100-300mbps. Some users have reported bit rates as high as 700mbps. If the bit rate is high enough the PC's GPU cannot keep up and the video plays with extreme artifacting, and users that experience this report a corrupted output video when it is in fact a high bit rate instead. Here is a screenshot of my results rendering the same 22-second video at custom bit rate 32mbps (top) and the default high quality preset (bottom), with the log output underneath:

The top file is about 32mbps, the bottom file is about 530mbps. After a large file is imported to a video editor, the issue is not present in a final rendered video because the bit rate is reduced by the video editor. The workaround is to ignore the high quality preset and use a custom bit rate instead.