Could The US Defend From An Invasion of the Homeland

Sounds about right. No a nation could project the necessary force and the attempt would likely result in the nation trying so being reduced to a nuclear waste land.
A basic principle that has been in effect is that only a true lunatic would try to invade an nuclear power.

First off I did not watch the video. However a friend and I have discussed this possible scenario at length and we determined it to be currently not possible for a foreign entity such as China or Russia to invade the United States. The United States military is currently the only military in the world that has the capability to project it's forces anywhere on a grand scale and most importantly the ability to sustain them.

There is so much wrong with this it defies description. Neither the Soviets in their heyday nor the Chinese at any point have the sealift or force projection platforms necessary to achieve such a feat - and that assumes that the US Navy is asleep at the switch. They'd be able to throw a punch at our Air Force of they achieved complete surprise, but even then American air forces are so numerous and dispersed that the remainder would assure at minimum airspace would be contested. A handful of submarines would lay waste to any such assault. Even if they landed, how they would traverse such vast territory surely full of armed partisans and numerous difficult natural obstacles is a question I don't think they could answer.