Nikolay Sivov (@nsivov) commented about dlls/mfmediaengine/main.c:
if (FAILED(hr = media_engine_create_video_renderer(engine, &grabber_node))) WARN("Failed to create video grabber node, hr %#lx.\n", hr);
if (FAILED(media_engine_create_video_effects(engine, &video_effects)))
WARN("Failed to create video effect nodes, hr %#lx.\n", hr);
This is missing 'hr' assignment.