What happens to the bubbles in this CPU thermal paste? (video)

I’ve been studying the best method to apply thermal paste and currently thinking the spread method might seem best where you spread an even thin layer across the whole CPU and then apply the heat sink, shown in the photo below. However I’m concerned about bubbles that could be trapped within uneven surfaces under the heat sink, it makes sense to me anyway that the bubbles would not be able to escape unless they squeezed out the side, and it would be hard for them to squeeze all the way from the center to the edge with a thin layer of paste spread across the CPU, or even if the layer was thicker. It seems like the thermal paste does not have thin enough viscosity to allow a small bubble to travel all the way out to the side.

But in this video the guy uses a stencil to apply the paste in dots across the CPU, and you can see when he smashes the plexiglass down on the CPU the bubbles seem to disappear into the paste, and I’m not understanding where the air went or if the bubbles are totally gone. What exactly is happening Here? Are the bubbles moving out the side but you just can’t see them through the thickness of the paste or something? Thanks.

EDIT: Also in this video, the bubble seem to disappear also, this video is actually of the spread method.