I need a scroll in my film so I came up with this.
There were a lot of constraints and expressions for this so I used pymel scripts to do all that for me (code is on my bitbucket site under randomMelAndPymel.py)
how i works:
each of the curl controls has a locator that has the same y position as the control unless the control is on the far side of the other control
that locator drives set driven keys on its curl chain and bend deformer fix
if the bottom locator is above a bind joint (actually reference joints off to the right in the video) that joint is constrained to the bottom curl otherwise its constrained to the top
I was a little lazy with the orientations(lack of sleep due to last week of term) so I couldn't use a parent constraint and had to use separate point and orient constraints.