Yes, you can have custom masking of sensitive user data in Fullview.
With the the masking mechanism, you can identify the HTML selectors (ID or class) that you want to hide, and then our replay and cobrowsing engine will completey mask the content of the input fields, not based on regular expressions.
When our engine captures your DOM, if it finds specific html elements that were specified to be masked, the engine doesn't read the content inside. Instead it directly skips to the next html element. So the data is not captured and then masked but instead it's never captured.