This is not a pyroclastic flow and doesn’t look even remotely similar. The problem is that you’re comparing a very close up image of some lava falling on a camera to videos taken from tens of miles away from Mt St Helens. The scale and nature of the event are completely different.

Weirdly if you are going to be hit by a pyroclastic flow then it won’t be moving across your field of view at all. It’ll just be getting bigger and angrier–looking for the minute or two that you have left in your life.