Analysis logic of all the screenshots was added to conversion engine, and in the case of appearance of gray screenshots, their automatic re-creation is done using more complex and long method (fast ffmpeg screenshots creation in some cases produces gray screenshots, evenly distributed throughout the video).
If streaming format files (flv, mp4) are uploaded manually, now the engine will still upload them to the conversion server to verify that they are ready for streaming (metadata for flv, moov container for mp4).
Website and in admin panel uploaders were extended to check 413 nginx error, which appears if uploaded file has a size greater than allowed. Now correct message is displayed instead of error code.
Few small corrections and bugs.