import urllib, re, string

pattern = re.compile("""<img id="animation-image" title="[^"]*" alt="[^"]*" src="([^"]*)" />""", re.DOTALL)

url = 'http://weatheroffice.ec.gc.ca/radar/index_e.html?id=XGO'
agent = urllib.URLopener()

doc = agent.open(url).read()
	
match = pattern.findall(doc)
print 'http://weatheroffice.ec.gc.ca/radar/' + match[0]