Other concepts are using tube-and-wing or flying wing embodiments. But long slender wings need more material to stiffen the slender structure. Just look at NASA/AeroVironment Helios, which ripped itself apart in a modest wind. Using centrifugal stiffening as a design element within the TURN concept eliminates the aerodynamic/structural tradeoff, and permits much better airfoils than standard practice will allow... nearly three times more efficient to be precise. By reducing that much structural material the TURN system carries much more battery mass. Most HALE aircraft cap out at about 20-25% battery mass, nearly 80% of the TURN vehicle weight is allocated for energy storage.
Now outdated: Note for moderators (who I assume scan new comments): Some of this users comments have shown up dead, probably because he's a new user who made a bunch of comments quickly. It would be nice if you could come and revive them.
For the solar, truly eternal case (which isn't strictly possible because sooner or later you're going to lose a bearing or blow a capacitor or something), I think the limiting factor would be less on the aerodynamic side and more on the power-to-weight ratio you're able to achieve with solar.
A lot of that is going to depend on things like power system efficiency, latitude, and altitude which makes it hard to give a definitive yea or nay on whether this is feasible. I'm not really an expert in power systems but from an aerodynamic perspective it seems at least within the realm of possibility.
Like anything, the details of the implementation are going to make it or break it but there's not enough concrete info in the video.