How to add a path filter to views 3 in Drupal 7? This doesn't have to do with contextual filters but is it possible to add a filter criterion to views so that it filters the aliased path to a node? 

Content:Path is available as a display field but why not as a filter too? Kind of similar question to this
Try the Views URL alias module.

The 'Views URL alias' module allows Views to be filtered by path aliases.
This module is useful if your website uses heirachical paths. It allows you to filter and sort a view by URL aliases. When combined with the Views bulk operation (VBO) module you can apply operations to a specific section of your website based on a URL alias.

Note that Currently, only node aliases are supported.