For maximum esoterica, and for a fun oneliner, and to learn a little about itertools:
def strip_suffix(filename):
"""
>>> video.mp4
video
>>> video.extra.mp4
video.extra
"""
return ''.join((name_dot[0] + name_dot[1] for name_dot in itertools.zip_longest(filename.split('.')[0:-1], '.', fillvalue='.')))[0:-1]
Note: this is just for fun. Do not use this.
Use os.path.splitext
instead