Using LR6.1 on OS X 10.10.4, Lightroom does not play MP4 videos taken with a smartphone (Lumia 930). Instead of the video, Lightroom only shows a solid green rectangle, both in the thumbnails/raster view and in the single-photo view. I've tried to switch off the GPU in the general settings, but that didn't change anything. When I add the identical MP4 files to Lightroom 5.7 on the same machine, all videos just show and play fine. What's wrong here? Thanks!