<p>I want to skeletize the surface mesh. For that I need to export .STL from Solidworks and then convert that into .OFF file to be able to use it in CGAL library for skeletonzation. How can I do this?</p>

One aspect of having this level of control with 3d printing of a model is the removal of the need for supports and the attendant post-processing. In the case of the model shown in the video, some effects are created by printing the continents in a conformal manner that would otherwise be impossible with conventional 3d printing. Cosmetically, the results of the "5d" printer are superior in this example.
There would also be some structural benefit for models with high organic content, that is curves and bulges, as opposed to orthogonal designs. Even with orthogonal designs, one can achieve stronger parts with cross-layered plastic in all directions, rather than being limited by x and y filament layers.
I see on the web site that one can exchange tool heads as well. One could print a 3d model, layering the filament on all the surfaces, then use a tool head change to a milling bit and smooth the surface under CAD control.  Alternatively, one could use foam or wood and mill a model shape to be covered with a 3d printed material.
Considering the relative novelty of this product, it's likely that many aspects of the creative utility have yet to be discovered!