Getting the bytes value.

common.py

# The code which i am writing underneath is going to be a part of common.py in extractors folder.
# I am simply declaring a new function. If you have something else in mind then do tell me

def get_bytes(self, url):
    """Partially download the final webpage to get the bytes value."""
    request = compat_urllib_request.Request(url)
    request.get_method = lambda : 'HEAD'
    response = compat_urllib_request.urlopen(request)
    return response.info().getheader('Content-Length')
    
# After this in any info extractor we can call it by:

bytes = self.get_bytes(final_url)

# And then in the info dict we can return:

return [{
    'id'       : video_id,
    'url'      : final_url,
    'ext'      : ext,
    'title'    : title,
    'thumbnail': thumbnail_url,
    'length'   : bytes,
}]

# What do you say ?