old_contents: // The code is also available at:
  // https://ee-api.appspot.com/ae2e427b6f82c5a2cbf8e91403724604
  
  var scale = 200; // in metres
  
  var gfcImage = ee.Image('UMD/hansen/global_forest_change_2013');
  var grid = ee.FeatureCollection('ft:1twk3A1sU5XNeWBSezKMXoUrpIkHqJrIRQlh-JcUV');
  var forest2000Image = gfcImage.select('treecover2000').divide(100);
  var forestArea2000Image = forest2000Image.multiply(ee.Image.pixelArea());
  
  var forest2000 = forestArea2000Image.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  var taskParams = {
   'driveFolder' : '',
   'fileFormat' : 'CSV'
  };
  
  Export.table(forest2000, 'Tree_cover_area_in_2000_per_cell', taskParams);
  
  var lossImage = gfcImage.select('loss');
  var totalTreeCoverLoss = forest2000Image.mask(lossImage);
  var totalTreeCoverLossArea = totalTreeCoverLoss.multiply(ee.Image.pixelArea());
  
  var totalLoss = totalTreeCoverLossArea.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  Export.table(totalLoss, 'Gross_tree_cover_loss_per_cell', taskParams);
  
  var gainImage = gfcImage.select('gain');
  var gainOnly = gainImage.and(lossImage.not());
  var gainOnlyArea = gainOnly.multiply(ee.Image.pixelArea());
  
  var totalGain = gainOnlyArea.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  Export.table(totalGain, 'Gross_tree_cover_gain_per_cell', taskParams);
  
new_contents: /* The code is also available at:
     https://ee-api.appspot.com/ae2e427b6f82c5a2cbf8e91403724604
     where it can be directly executed */
  
  var scale = 200; // in metres
  
  var gfcImage = ee.Image('UMD/hansen/global_forest_change_2013');
  var grid = ee.FeatureCollection('ft:1twk3A1sU5XNeWBSezKMXoUrpIkHqJrIRQlh-JcUV');
  var forest2000Image = gfcImage.select('treecover2000').divide(100);
  var forestArea2000Image = forest2000Image.multiply(ee.Image.pixelArea());
  
  var forest2000 = forestArea2000Image.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  var taskParams = {
   'driveFolder' : '',
   'fileFormat' : 'CSV'
  };
  
  Export.table(forest2000, 'Tree_cover_area_in_2000_per_cell', taskParams);
  
  var lossImage = gfcImage.select('loss');
  var totalTreeCoverLoss = forest2000Image.mask(lossImage);
  var totalTreeCoverLossArea = totalTreeCoverLoss.multiply(ee.Image.pixelArea());
  
  var totalLoss = totalTreeCoverLossArea.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  Export.table(totalLoss, 'Gross_tree_cover_loss_per_cell', taskParams);
  
  var gainImage = gfcImage.select('gain');
  var gainOnly = gainImage.and(lossImage.not());
  var gainOnlyArea = gainOnly.multiply(ee.Image.pixelArea());
  
  var totalGain = gainOnlyArea.reduceRegions({
   'collection': grid,
   'reducer': ee.Reducer.sum(),
   'scale': scale,
  });
  
  Export.table(totalGain, 'Gross_tree_cover_gain_per_cell', taskParams);
  
subject: Update GEE link description