Do you have an error in the first query under the 'Choosing what gets Trimmed' section? Currently it shows the query as:
SELECT Result = '[' + TRIM(n) + ']' ,
FirstLetter = ASCII(SUBSTRING(TRIM(n), 1, 1)),
LastLetter = ASCII(SUBSTRING(TRIM(n), LEN(TRIM(n)) - 1, 1))
FROM( VALUES (',Broncos, Raiders, Chargers, Chiefs ') ,
(',Texans, Jaguars, Colts, Titans, ' ) ,
AS a (n);
And the results show rows with missing commas at the beginning and end, but the actual TRIM commands "TRIM(n)"does not list that commas should be removed (which I think is what you intended).
An interesting new feature in SQL Server though, thanks for the article highlighting that it finally exists.