$googleClient->setDefer(true);

$autorization =  json_decode($googleClient->getAccessToken())->token_type.' '.json_decode($googleClient->getAccessToken())->access_token;

$headers = [
    'authorization' => $autorization,
    'alt' => 'media'
];

$request = new Google_Http_Request(
    $report->downloadUrl,
    'GET',
    $headers
);

$request->enableExpectedRaw();
$response = $googleClient->execute($request);

$googleClient->setDefer(false);

$client->setDefer(true);

// Call the YouTube Reporting API's media.download method to download a report.
$request = $youtubeReporting->media->download("");
$request->setUrl($reportUrl);
$response = $client->execute($request);

file_put_contents("reportFile", $response->getResponseBody());
$client->setDefer(false);

function downloadReport(Google_Service_YouTubeReporting $youtubeReporting, $reportUrl, &$htmlBody) {
  $client = $youtubeReporting->getClient();
  $client->setDefer(true);

  // Setting 'alt' param here fixes the first half of the issue
  $request = $youtubeReporting->media->download("", array("alt" => "media"));
  // Correctly updating the URL fixes the second half
  $request = $request->withUri(new \GuzzleHttp\Psr7\Uri($reportUrl));
  $response = $client->execute($request);

  file_put_contents("reportFile", $response->getBody());
  $client->setDefer(false);
}