While this is a good illustration of how to leverage the output of sp_helptext, I would caution against using this in a production environment or without the benefit of a test platform. Many stored procedures I have seen perform the same activity against different record-sets depending on a condition, and these stored procedures will often contain all of these different updates together. So if a set meets condition A, then a column value is set to X, and if the next recordset meets condition B, then the column value is set to Y, etc.
Relying up a quick update like this to make a change may have a much larger impact upon your code if you are not careful. A quick review of the code before using this tool would help prevent this, but also a more thorough check of the code afterwards. Always look for possiblilities that there are unintended results.
An analog to this problem I am describing would be if you were using the "Find and Replace' tools within SSMS . For example, you are editing a comma-separated listing of address data to be placed into a table, and you decide to replace occurrences of ' ' with an empty field ''. Instead of typing the field exactly as I have shown it, you type ' ' reasoning that this will capture all of the shorter blank strings and save you the work of having to search for all of them not captured by searching for ' '. It works! But the unintended consequence is that all strings of words in your CSV are now one big long word.