Kind of confused how this work, doesn't my browser have to support this compression as well? Like watching it on deepmind's website, doesn't there have to be another layer of compression for me to watch it?
Video uses codecs which encode information in frames of various types; in particular, the I-frame is essentially a self-contained image, a bit like JPEG, and the P-frame only encodes the changes from the previous frame.
The choice of when to have an I-frame or a P-frame is arbitrary, but the rendered video will look the same. However, too many I-frames can bloat the filesize, and too few can degrade the appearance significantly as errors add up.
They act on a codec parameter related to the I-frame, to pick better rules for good compression without visible errors in the P-frame.
The decoder in your player can be considered a programmable machine, and the job of the encoder is to emit an optimal program that achieves or approximates the desired results. Just like any program compiler, there will be more than one way to do it, depending on how much space and time you are willing to dedicate to the job.