user21521: I'm new to English chess notation and have never read or heard chess commentary in a broadcast or publication form.
I'm trying to decipher the following commentary

ICGA's footnote to caption:
ACM CCC, Washington DC, Round 4, Dec. 5th, 1978: ECO C48, Four Knights. 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Nd4 5. Bc4 Bc5 6. Nxe5 Qe7 7. Bxf7+ Kf8 8. Ng6+ hxg6 9. Bc4 Nxe4 10. O-O Rxh2!! {cf. the photo} 11. Kxh2 {hastening the loss} Qh4+ 12. Kg1 Ng3 13. Qh5 {ineffectual delay} gxh5 14. fxg3+ Nf3# {perhaps uniquely blocking a check, giving a double check and mating simultaneously; "the most beautiful combination created by a computer program to date... computer chess witnessed the start of a new era." (Levy and Newborn, 1991)}.

I think I have figured out the series of moves in paired notation. But what does the parenthesized part (e.g. {hastening the loss}, {ineffectual delay}, etc.) exactly refer to? Are they a part of commentary (spoken during the match) or additional information that has been added afterward?

user20721: The  comments in braces means that the move before had the effect noted in that set of  { }s  .  It is just annotating the game to explain the moves. 
It may have been spoken during the match if it were broadcast,  but it was definitely  printed in the game summary later at the link you provided to bell labs.   
The !!  means that the move was excellent, often unexpected, and winning. 
In this case the #  means mate.  

user19877: Here is what all of that means:
"ICGA's footnote to caption: "There is a picture above all this, and they are just noting the game that had been played in the picture. The ICGA is the International Computer Games Association.
"ACM CCC", Is the name of the tournament/organizers of the tournament, "Association for Computing Machinery" "Computing Community Consortium"
"Washington DC, Round 4, Dec. 5th, 1978" was the location, the 4th round in the tournament, and the date.
"ECO C48" is the Encyclopedia of Chess Openings classification code for the opening of the game: C48 - Four Knights: 4.Bb5, replies other than 4...Bb4.
"the most beautiful combination created by a computer program to date... computer chess witnessed the start of a new era." (Levy and Newborn, 1991).
This was a quote from the book "How Computers Play Chess" by noted early computer chess pioneer International Master David Levy and Monty Newborn.
The rest of it is just commentary, and most likely, it was not during the game. "cf." is the common English abbreviation for "compare" coming from the Latin: confer/conferatur, the plus sign "+" is the common symbol for "check", "!!" is the common symbol for an extraordinary move", and the pound sign "#" is the common symbol for checkmate. You can find a complete list here.
While most people today would use parenthesis "()" instead of braces "{}" first, they were just used to set off the comments, and to embed one within the other.
Summing up, the only thing that you will find common going forward is the general tournament/data information, but especially the ECO codes (not that you need to memorize them, but you will see them often), and especially the chess annotation symbols. Those chess annotation symbols are something that you should learn if you are going to read a lot about chess in the future.
 [FEN ""]

 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Nd4 5. Bc4 Bc5 6. Nxe5 Qe7 7. Bxf7+ Kf8 8. Ng6+ hxg6 9. Bc4 Nxe4 10. O-O Rxh2 {cf. the photo.} 11. Kxh2 {hastening the loss.} Qh4+ 12. Kg1 Ng3 13. Qh5 {ineffectual play.} gxh5 14. fxg3+ Nf3#


21521: <p>I'm new to English chess notation and have never read or heard chess commentary in a broadcast or publication form.</p>
<p>I'm trying to decipher the <a href="https://www.bell-labs.com/usr/dmr/www/ken-games.html" rel="nofollow noreferrer">following commentary</a></p>
<blockquote>
<p>ICGA's footnote to caption:</p>
<p>ACM CCC, Washington DC, Round 4, Dec. 5th, 1978: ECO C48, Four Knights. 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Nd4 5. Bc4 Bc5 6. Nxe5 Qe7 7. Bxf7+ Kf8 8. Ng6+ hxg6 9. Bc4 Nxe4 10. O-O Rxh2!! {cf. the photo} 11. Kxh2 {hastening the loss} Qh4+ 12. Kg1 Ng3 13. Qh5 {ineffectual delay} gxh5 14. fxg3+ Nf3# {perhaps uniquely blocking a check, giving a double check and mating simultaneously; &quot;the most beautiful combination created by a computer program to date... computer chess witnessed the start of a new era.&quot; (Levy and Newborn, 1991)}.</p>
</blockquote>
<p>I think I have figured out the series of moves in paired notation. But what does the parenthesized part (e.g. {hastening the loss}, {ineffectual delay}, etc.) exactly refer to? Are they a part of commentary (spoken during the match) or additional information that has been added afterward?</p>
 20721: <p>The  comments in braces means that the move before had the effect noted in that set of  { }s  .  It is just annotating the game to explain the moves. </p>

<p>It may have been spoken during the match if it were broadcast,  but it was definitely  printed in the game summary later at the link you provided to bell labs.   </p>

<p>The !!  means that the move was excellent, often unexpected, and winning. </p>

<p>In this case the #  means mate.  </p>
 19877: <p>Here is what all of that means:</p>

<p>"ICGA's footnote to caption: "There is a picture above all this, and they are just noting the game that had been played in the picture. The ICGA is the <a href="https://icga.org/" rel="noreferrer">International Computer Games Association</a>.</p>

<p>"ACM CCC", Is the name of the tournament/organizers of the tournament, "<a href="https://www.acm.org/" rel="noreferrer">Association for Computing Machinery</a>" "<a href="https://cra.org/ccc/" rel="noreferrer">Computing Community Consortium</a>"</p>

<p>"Washington DC, Round 4, Dec. 5th, 1978" was the location, the 4th round in the tournament, and the date.</p>

<p>"ECO C48" is the <a href="https://en.wikipedia.org/wiki/List_of_chess_openings" rel="noreferrer">Encyclopedia of Chess Openings classification code</a> for the opening of the game: C48 - Four Knights: 4.Bb5, replies other than 4...Bb4.</p>

<p>"the most beautiful combination created by a computer program to date... computer chess witnessed the start of a new era." (Levy and Newborn, 1991).
This was a quote from the book <a href="https://rads.stackoverflow.com/amzn/click/com/B0026QP89Y" rel="noreferrer" rel="nofollow noreferrer">"How Computers Play Chess"</a> by noted early computer chess pioneer <a href="https://en.wikipedia.org/wiki/David_Levy_(chess_player)" rel="noreferrer">International Master David Levy</a> and Monty Newborn.</p>

<p>The rest of it is just commentary, and most likely, it was not during the game. "cf." is the common English abbreviation for "compare" coming from the Latin: confer/conferatur, the plus sign "+" is the common symbol for "check", "!!" is the common symbol for an extraordinary move", and the pound sign "#" is the common symbol for checkmate. <a href="https://en.wikipedia.org/wiki/Chess_annotation_symbols" rel="noreferrer">You can find a complete list here.</a></p>

<p>While most people today would use parenthesis "()" instead of braces "{}" first, they were just used to set off the comments, and to embed one within the other.</p>

<p>Summing up, the only thing that you will find common going forward is the general tournament/data information, but especially the ECO codes (not that you need to memorize them, but you will see them often), and especially the chess annotation symbols. Those chess annotation symbols are something that you should learn if you are going to read a lot about chess in the future.</p>

<pre><code> [FEN ""]

 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Nd4 5. Bc4 Bc5 6. Nxe5 Qe7 7. Bxf7+ Kf8 8. Ng6+ hxg6 9. Bc4 Nxe4 10. O-O Rxh2 {cf. the photo.} 11. Kxh2 {hastening the loss.} Qh4+ 12. Kg1 Ng3 13. Qh5 {ineffectual play.} gxh5 14. fxg3+ Nf3#
</code></pre>
