我已经使用Google App Engine应用程序的YouTube数据API5个月了，没有收到服务不可用，503错误响应。但是今天，我得到了这个：
YouTubeError: {
'status': 503,
'body': '<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">n<html>n<head><meta http-equiv="content-type" content="text/html; charset=utf-8"><title>http://gdata.youtube.com/action/GetUploadToken</title></head>n<body style="font-family: arial, sans-serif; background-color: #fff; color: #000; padding:20px; font-size:18px;" onload="e=document.getElementById('captcha');if(e){e.focus();}">n<div style="max-width:400px;">n <hr noshade size="1" style="color:#ccc; background-color:#ccc;"><br>n n n <div style="font-size:13px;">n Our systems have detected unusual traffic from your computer network. Please try your request again later. <a href="#" onclick="document.getElementById('infoDiv0').style.display='block';">Why did this happen?</a><br><br>n <div id="infoDiv0" style="display:none; background-color:#eee; padding:10px; margin:0 0 15px 0; line-height:1.4em;">n This page appears when Google automatically detects requests coming from your computer network which appear to be in violation of the <a href="http://www.google.com/accounts/TOS">Terms of Service</a>. The block will expire shortly after those requests stop.<br><br>This traffic may have been sent by malicious software, a browser plug-in, or a script that sends automated requests. If you share your network connection, ask your administrator for help — a different computer using the same IP address may be responsible. <a href="http://www.google.com/support/bin/answer.py?answer=86640">Learn more</a><br><br>Sometimes you may see this page if you are using advanced terms that robots are known to use, or sending requests very quickly.n </div><br>n n IP address: 74.125.19.24<br>Time: 2012-10-09T17:48:20Z<br>URL: http://gdata.youtube.com/action/GetUploadToken<br>n </div>n</div>n</body>n</html>n',
'reason': 'Service Unavailable'
}
我正在使用YouTube上传用户的视频，以及显示现有视频（用户仅输入视频URL）。有谁知道它不起作用的可能原因？
我正在使用gdata python库。我在视频模型中定义了yt_service属性：
def yt_service(self):
try:
return self._yt_service
except AttributeError:
yt_service = gdata.youtube.service.YouTubeService()
yt_service.developer_key = settings.SYNCR_YT_DEVKEY
yt_service.email = settings.SYNCR_YT_EMAIL
yt_service.password = settings.SYNCR_YT_PASS
yt_service.ProgrammaticLogin()
self._yt_service = yt_service
return yt_service
然后在创建上传表单时，查看调用yt_service.GetFormUploadToken以检索上传令牌。它在这里失败了。