MIT's Mediated Matter Group develops novel production methods that allow us to shape material in new ways. As part of their Additive Manufacturing of Optically Transparent Glass project, they've developed a 3D printer that can actually handle molten glass.
The FDM-style printer they've developed, called the G3DP, uses a "Kiln Cartridge" to heat the material to 1900 freaking degrees Fahrenheit. As for applications, it's apparently not for the tabletop-sized, vase-like objects you saw in the video; it seems they intend to scale this machine up with the intent of applying it to architecture. As they explain:
[Existing] digital design and construction technologies for product and building scale are generally limited in their capacity to deliver multi-functional building skins…. The Glass Printing project is an enabling technology for optical glass 3D printing at architectural scale designed to manufacture multi-functional glass structures and facade elements.