Find all file occurences of a search term on drive
I really like this code. Let me explain why in a few short sentences:

Typechoice:

You return an IEnumerable and not a List. This is awesome, because a List implies sorted entries and blocks some Types, that you can use with IEnumerable

Naming:

Your names are short, comprehensive and follow the naming conventions. There's not much more to say.

Program flow:

It is instantly obvious to the reader, what your program does and how it does that, simply by speaking english. This is very hard to accomplish, and I want to compliment you on that.

Choice of methods:

You explained very nicely why you chose EnumerateFiles() over GetFiles(). If you'd comment that, IMO your code would be perfect.