Ok I've uploaded the modified and working script to here:
http://wikisend.com/download/437498/youtube-dl
It seems to be working on my Nokia fine. Remember you will also need to download the getpass.py
posted by liquid217 above. You need to put the getpass.py in your /usr/lib/python2.5/site-packages

You need to place youtube-dl in
/usr/bin/

you need to make sure the permissions on the youtube-dl script are correct.

as root type:
chmod 755 /usr/bin/youtube-dl

You also need to go to mytube>preferences>more>youtube-dl and change
youtube-dl-x
to
youtube-dl
leave the rest of the options the same.
Good Luck!