Warrants have never been needed if there was probable cause.
If the cops saw you do something bad, and then saw that you have a camera that was running, they have probable cause for seizing anything that could provide evidence (e.g. the camera). This is nothing new.
Also, if you take that recording, and broadcast it over the internet, it is now in plain sight. No warrant is needed to do whatever they want to do with it.
A fishing expedition in which the cops didn't see you do something bad, but see that you have a camera that might show that you did something bad, that's a different situation.
Running a camera while you are riding is all well and good as long as you are behaving. If you are not behaving, and the cops see you do something, that camera just provided the evidence for conviction.
Manage what you record, very carefully, bearing in mind that it's not legal to exceed the speed limit, not even by 1 km/h.
P.S. this rider was an idiot; the unsafe overtaking is the most blatant problem.