why i can get nothing?

[contro opinion]

here is my code :
import urllib
import lxml.html
down='http://download.v.163.com/dl/open/00DL0QDR0QDS0QHH.html'
file=urllib.urlopen(down).
read()
root=lxml.html.document_fromstring(file)
tnodes = root.xpath("//a/@href[contains(string(),'mp4')]")
for i,add in enumerate(tnodes):
    print  i,add

why i can get nothing?
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