Не могу транслировать видео (PFFile) с сервера разбора

parse-server, похоже, не поддерживает потоковую передачу в Safari/iOS, и решение заключается в том, чтобы включить его с помощью экспресс и GridStore следующим образом:

parse-server-example\node_modules\parse-server\lib\Routers\FilesRouter

    {
key: 'getHandler',
value: function getHandler(req, res, content) {
var config = new _Config2.default(req.params.appId);
var filesController = config.filesController;
var filename = req.params.filename;
var video = '.mp4'
var lastFourCharacters = video.substr(video.length - 4);
if (lastFourCharacters == '.mp4') {

  filesController.handleVideoStream(req, res, filename).then(function (data) {

    }).catch(function (err) {
      console.log('404FilesRouter');
        res.status(404);
        res.set('Content-Type', 'text/plain');
        res.end('File not found.');
    });
}else{
filesController.getFileData(config, filename).then(function (data) {
  res.status(200);
  res.end(data);
}).catch(function (err) {
    res.status(404);
    res.set('Content-Type', 'text/plain');
    res.end('File not found.');
  });
 }
}
} , ...

parse-server-example\node_modules\parse-server\lib\Controllers\FilesController

_createClass(FilesController, [{
key: 'getFileData',
value: function getFileData(config, filename) {
return this.adapter.getFileData(filename);
}
},{
key: 'handleVideoStream',
value: function handleVideoStream(req, res, filename) {
return this.adapter.handleVideoStream(req, res, filename);
}
}, ...

parse-server-example\node_modules\parse-server\lib\Adapters\Files\GridStoreAdapter

... , {
     key: 'handleVideoStream',
     value: function handleVideoStream(req, res, filename) {
     return this._connect().then(function (database) {
     return _mongodb.GridStore.exist(database, filename).then(function     () {
  var gridStore = new _mongodb.GridStore(database, filename, 'r');
  gridStore.open(function(err, GridFile) {
      if(!GridFile) {
          res.send(404,'Not Found');
          return;
        }
        console.log('filename');
        StreamGridFile(GridFile, req, res);
      });
      });
      })
      }
      }, ...

Низ адаптера GridStore

function StreamGridFile(GridFile, req, res) {
var buffer_size = 1024 * 1024;//1024Kb

if (req.get('Range') != null) { //was: if(req.headers['range'])
  // Range request, partialle stream the file
  console.log('Range Request');
  var parts = req.get('Range').replace(/bytes=/, "").split("-");
  var partialstart = parts[0];
  var partialend = parts[1];
  var start = partialstart ? parseInt(partialstart, 10) : 0;
  var end = partialend ? parseInt(partialend, 10) : GridFile.length - 1;
  var chunksize = (end - start) + 1;

  if(chunksize == 1){
    start = 0;
    partialend = false;
  }

  if(!partialend){
    if(((GridFile.length-1) - start) < (buffer_size) ){
        end = GridFile.length - 1;
    }else{
      end = start + (buffer_size);
    }
      chunksize = (end - start) + 1;
    }

    if(start == 0 && end == 2){
      chunksize = 1;
    }

res.writeHead(206, {
      'Cache-Control': 'no-cache',
    'Content-Range': 'bytes ' + start + '-' + end + '/' + GridFile.length,
    'Accept-Ranges': 'bytes',
    'Content-Length': chunksize,
    'Content-Type': 'video/mp4',
  });

  GridFile.seek(start, function () {
    // get GridFile stream

            var stream = GridFile.stream(true);
            var ended = false;
            var bufferIdx = 0;
            var bufferAvail = 0;
            var range = (end - start) + 1;
            var totalbyteswanted = (end - start) + 1;
            var totalbyteswritten = 0;
            // write to response
            stream.on('data', function (buff) {
            bufferAvail += buff.length;
            //Ok check if we have enough to cover our range
            if(bufferAvail < range) {
            //Not enough bytes to satisfy our full range
                if(bufferAvail > 0)
                {
                //Write full buffer
                  res.write(buff);
                  totalbyteswritten += buff.length;
                  range -= buff.length;
                  bufferIdx += buff.length;
                  bufferAvail -= buff.length;
                }
            }
            else{

            //Enough bytes to satisfy our full range!
                if(bufferAvail > 0) {
                  var buffer = buff.slice(0,range);
                  res.write(buffer);
                  totalbyteswritten += buffer.length;
                  bufferIdx += range;
                  bufferAvail -= range;
                }
            }

            if(totalbyteswritten >= totalbyteswanted) {
            //  totalbytes = 0;
              GridFile.close();
              res.end();
              this.destroy();
            }
            });
        });

  }else{

//  res.end(GridFile);
        // stream back whole file
      res.header('Cache-Control', 'no-cache');
      res.header('Connection', 'keep-alive');
      res.header("Accept-Ranges", "bytes");
      res.header('Content-Type', 'video/mp4');
      res.header('Content-Length', GridFile.length);
      var stream = GridFile.stream(true).pipe(res);
   }
  };

P.S Оригинальный ответ дан здесь @Bragegs - https://github.com/ParsePlatform/parse-server/issues/1440#issuecomment-212815625 .