public GlobalJsonResult <EmptyResult> Append(int videoId, [FromBody] AppendFramesRequest request)
        {
            var video  = videoService.GetById(videoId);
            var frames = request.AppendFrameRequests
                         .Select(req => frameService.Initialize(1, req));

            video.AddFrames(frames);

            return(GlobalJsonResult <EmptyResult> .Success(HttpStatusCode.Created));
        }