Parentheses are a special character in Regular Expressions, so if you want to actually find them in the text, you have to remember to "escape" them by using a backslash.
If you look at davidfor's answer, you can see the correct backslashes in
ORANGE:
\(([0-9]+:[0-9]+)\)
... and the reason why parentheses are special in Regex is your inner portion. Parentheses allow you to "capture" text.
\(([0-9]+:[0-9]+)\)
Whatever is in between those special
RED parentheses gets "captured" in a group. So, in this case, all the
BLUE stuff becomes "Group 1".
Now, if you take a look at your Replace:
<b><sup>\1</b></sup>
The
BLUE "\1" says "stick Group 1" here.