I won't go into much detail because this could be removed for soapbox/political/propaganda reasons but I will add a bit of context for curious readers: the video is edited from two talks in 1974 and starts with Welch quoting short passages from his remarks in December 1958. The 1958 presentation took place over two days and was adapted into the 150+ page 'Blue Book of the John Birch Society', the full text of which I'll link below.

So you have the initial problem of this clip being cherry picked by whoever made the youtube video quite recently from multiple 1974 talks (the first of which is 2 hours and is linked below). Then the '74 talks themselves are cherry picked edits chosen from many claims Welch made 15 years earlier. Far more distressingly, the video is not just cherry picking passages but it is edited in a highly misleading fashion to make the quotes look more relevant to the present day. For example at 1:00 mark there is an edit, both the passages before and after the edit remove the clear context about the Soviet/Global Communist conspiracy (and Welch himself edits a lot of context for example the whole bit about how Sputnik is what leads to the numbered list of 'predictions').

Not surprisingly modern viewers might not find the 'predictions' to be so 'chillingly prescient' if the quotes included how the US in '59 (or even '74) was about to fall into "a world-wide government ruled by the Kremlin" (this quote from the book follows the part before the 1:00 edit above).

I only researched the first 90 seconds of the video but the most egregious and clearly deceptive edit IMHO was removing the single word "Communists" from the passage "Here are the Communists' aims for the United States ...". Here is a link to the quote in the full remarks. I suspect there's a good joke about editing the Communist conspiracy angle out of Robert Welch's views and winding up with something sounding pretty reasonable but I digress.

The unedited passages the above are drawn from can be found in parts V and VI from the full text here:

https://archive.org/stream/TheBlueBook/MicrosoftWord-Document1_djvu.txt

Is there a tldr? I'm glad you asked, part VII immediately following these two passages (and in the '74 speech) wraps up Welch's predictions:

In summary, gentlemen, we are losing, rapidly losing, a cold war in which our freedom, our country, and our very existence are at stake.

I would say history has not treated this view (or Welch's others) very kindly.