gdataclient = python-gdata, except python-gdata is version 1.0.10 and gdataclient is 1.0.9
I think that if you have gdataclient, you don't need python-gdata to run mytube, though I am not sure.
I don't know if mytube uses any function that is available in 1.0.10 and it isn't in 1.0.9.
The most important difference between versions is 1.0.10 supports picasa web albums (I needed this function for maemo wordpy).

So the idea is, if you have erminig installed, try mytube whitout to install python-gdata.