I am using beautifulsoup to parse all img tags which is present in \'www.youtube.com\'
The code is
import urllib2
from BeautifulSoup import Beautiful
I had the similar problem. I couldn't find all images. So here is the piece of code that will give you any attribute value of an image tag.
from BeautifulSoup import BeautifulSoup as BSHTML
import urllib2
page = urllib2.urlopen('http://www.youtube.com/')
soup = BSHTML(page)
images = soup.findAll('img')
for image in images:
#print image source
print image['src']
#print alternate text
print image['alt']