Registered users filter

Not sure what you ment by 'registered users'?
Do you mean Your Leads who have filled out any Marketo form on your site?

No, like people who've created a login and password to gain access to your website. I think for us this info is captured in Clickshare and then Clickshare is supposed to feed this data to Marketo. We're trying to see if there's a way to view this from the Marketo side?

Unless that platform API's that information back to Marketo, you will need to set up some custom fields to capture this.
For example, an API service could be set up to update/append records in your Marketo with a true or false field and a date field to let you know that lead looged in to your platform equals true and on by date.

We do something similar with our trial download software where we integrated it into Marketo.

Thanks, this is helpful! We discovered a CSuserID field that pulls in exactly what we need. 

Thanks for your help!