У вашего броузера проблема в совместимости с HTML5
How to insert an image from the web in Python.
from Tkinter import*
import urllib
import base64
root = Tk()
URL = "http://image.doc2pdf.net/temp/images33.gif"
a = urllib.urlopen(URL)
raw_input = a.read()
a.close()
b = base64.encodestring(raw_input)
image = PhotoImage(data=b)
label = Label(image=image)
label.pack()
root.mainloop()