Couldn't watch the video, but US power has been declining since the end of WWII where it had literally half the world's wealth, security unheard of before in history, virtual control of both oceans, every other competitor either destroyed or seriously damaged in the war.
WWII's subsequent destruction of Europe and much of Asia was a blessing for the US and brought it out of the depression. US production, already the world's largest, had doubled at the end of the war, and gave way to the 50s, the peak of US self-image. It took over most of the old British Empire possesions abroad, kicking France out of most of the rest, and devised a 'grand strategy' for what is called 'the grand area', basically world domination.
Though direct control is fading, there's still no serious contenders, China is a poor, backwards mostly rural country for a good time yet, and mostly an assembly plant for Western corporations. US power may be declining but still has the world's largest economy, by far the biggest army expenditure (always a main point of US power and exercised as such), and natural advantages that no other state or collection of states comes even close to.
Comparing the US to most other states is not entirely fair, of course, it's a collection of rather large states, in total sizing up to some of the biggest Asian countries, combined with mostly Anglo-European culture and levels of industrial and technological sophistication.
