[rrmoelker]

I couldn't quite figure out from the video if it was an early launch detection system and/or a signal jammer. Cause the video mentions both.

A cursory glance at the Wikipedia article also didn't clear it up. Does anyone know?

[sciurus]

It was a detection system, but it operated on frequencies that already in use by shortwave broadcast stations (much more prevalent then than now), amateur radio operators, etc and interfered with them.

You can get more details on how it and similar systems work at https://en.m.wikipedia.org/wiki/Over-the-horizon_radar

[reportgunner]

From reading the wikipedia article it seems like it was primarily a launch detection system that had a side effect of jamming signal.