Is it possible to use the auto-rig to create a rig used to scale a character mesh, like this https://vimeo.com/35491262 [vimeo.com]?

no.
the auto-rigs are just for rigging an existing mesh.

if you want to build meshed parametrically you might have a look at makeHuman http://www.makehuman.org/ [makehuman.org]

I am familiar with MakeHuman. I don't believe that is what this is. This is a rig that scales parts of the mesh via the bones. My question, can you scale the autorig bones to scale the corresponding parts of the mesh?

The rig in the video was built in softimage.

I suppose you could scale the mesh using the bones - but I would advise against it - it would break lots of things.
making variations of a mesh is better done in modeling (either by hand or through a parametric app like makeHuman) or by building your own system - which you could do in Houdini…

but the supplied auto-rigs can't do what you're asking, as they were never designed to do anything like this.

Not exactly what you are looking for and this may sound slightly sacrilegious but I have been using Make Human and Maya's Human IK system to achieve something similar - Make Human will export human ik compatible rigs

The auto rigger and re-targeting in Human Ik are very mature and the rigs and weights come across fine into Houdini

It is the only reason I would open maya these days. I'd rather do it all in Houdini but I found it is not possible without months of rnd

I think makeHuman is a great idea (and a pretty good application) and I'd love to see more Houdini friendly features - there are no plans that I know of for this at the moment but makeHuman is open source so there is nothing stopping anyone from adding features

after a bit of a thought I realised that makehuman is really just driving blendshapes
It would be fairly trivial to export the extremes of each parameter and use them to drive deformation shapes post deform in houdini

will have a peak when I have a mo

cheers