From further information that's emerged:

- The site captured in the video, the Gyirong Port border crossing between China and Nepal, was struck by the flood roughly seven minutes after the presumed avalanche thought to have triggered the event.

- Flood inundation is seen up to 800 m (2,600 ft) above river level, and the camera position in the video at approximately 20--25m (roughly 6--8 stories) above ground level was engaged in the debris flow.

- It would take a fit person 4--8 minutes to climb even 250m or so above ground level, presuming instant notification and a clear evacuation path. Even with an instant warning of upstream conditions survival was overwhelmingly unlikely.

- Subsequent footage appears to show complete obliteration off all structures, with no trace remaining. This is based on preliminary imagery, without precise location information, and in a landscape changed beyond all recognition.

- Astoundingly, two survivors from the Port are mentioned in Wikipedia presently.

Though yes, one of the peculiarities of flood risk is that elevation equals safety. That's modulo a number of other factors though.

In particular, with an event of this magnitude, wind blast is a major effect. Toward the end of one video a line of buses in a car park is seen shifting backward, I suspect due to wind. These can reach well above hurricane force, and of course carries its own debris and threats, where even grass and straw can penetrate deeply. There's also the risk of secondary landslides and the like in steep terrain. One of the regions affected by this event has an etymology from "mud wall", which may be a reference to the geology of the canyon walls themselves. Those could easily be unstable.

Best option is to be lucky and not be there when things go horribly wrong.