The first two videos are uploaded by CentripetalWorlds. Both feature O’Neill cylinders, video one appears to show, the construction of an O’Neill cylinder.
Two rotating O’Neill cylinders (warning: annoying sound, please mute volume).
A different but related design, the Kalpana One:
The Kalpana One is an interesting design, and quite suitable for the first generation of space settlements (O’Neill cylinders have been considered as a second generation space habitat since they were designed).
For a technical discussion of O’Neill cylinders, by no one less than O’Neill himself, see here.