How to Use Contextual Filters
You need to rewrite the output of the field and use PHP for the text string manipulations.

Two modules can help you do that. Note that you'll likely choose one of these two modules. they aren't dependent on each other. They can both help you get what you want in different ways.


Views PHP
Computed Field


You might need to turn the title off and create it instead in the View header using "Global: text" and turning tokens on their. The token for username (which is "[name]" will use the value from the written output you've used when defining the field.