Outdoor activity lends itself perfectly to Glass's first-person perspective. It's no coincidence that Google's epic Glass promo stunt showcased skydivers hurtling through San Francisco airspace.
Hiking around an active volcano as a cyborg? Check
You really can capture environments and moments that you'd never normally think about trying to shoot. I don't use the video feature much (it kills Glass's already pretty awful battery life), but rock climbers and other adventuresome outdoor sporty types can capture footage that would otherwise be impossible short of a GoPro.