I am trying to set Video Language for the video upload using Google's Youtube API. Here is the upload interface look like.

I try to set it up using defaultLanguage snippet, as shown below, but it did not do anything.
Is it possible to set the Video Language to something specific (say French)? Please help.
def initialize_upload(youtube, options):
tags = None
if options.keywords:
tags = options.keywords.split(",")
body=dict(
snippet=dict(
title=options.title,
description=options.description,
tags=tags,
categoryId=options.category
),
status=dict(
privacyStatus=options.privacyStatus,
defaultLanguage="en", # <<<< ====== this did not work
publishAt=options.publishAt
)
)