Practical Question: can I fly down a windy river or hiking trail?

[pedz]

The purpose of the 2nd observer is to keep the drone within the line of sight. What I'd like to do is fly down a windy creek or river. Or, similarly, fly down a hiking path in the woods. There is no way that any single observer is going to be able to keep the drone in sight. An example of this would be the footage of drones following the bikes down mountain slopes. They go WAY far and down crazy complex paths. Is that all just 100% illegal but they do it anyway or what?

 

[Pygar70]

As soon as your spotter loses sight of the drone, you're flying illegally. I would suggest that most of the FPV footage you see online does not conform to local regulation.
Spare a thought for Australians: VLOS must be maintained by the pilot! While you can apply for an exemption, use of goggles here is effectively banned unless you're flying indoors or as a member of a model aircraft association that has approval to fly FPV on their premises.

 

[Texas Red]

VLOS. Lol. I can see 10 miles! Not