In Groups and Users we will see different permissions and if there is a Salesforce, Salesloft, or a legacy version of another integration, you will see a Guest role.
A subgroup will be created after setting up an integration to Salesforce, or after there has been a legacy version of another integration.
When a user has the 'guest' permission in a Guests group, they have accessed the Integrated program through the Vidyard app.
Vidyard has automatically placed them into the 'guest' role to enable access to the Guests account, where the videos will be stored.
If you log in to the dashboard and go to the Guests group in any role, you will only see your players and videos.
If users are in other roles, then they have been manually moved by someone with user/role editing ability (likely by an Admin in the parent group). You can edit the permissions that these roles get separately from the generic guest role - so you would usually take advantage of this if you need some people to have a different level of access than the limited Guest role (i.e. view analytics).
If you have people in a user role and this was a mistake in setup, it's safe to remove them from that box. When they log into the VY app on Salesforce again, it will place them back into the guest role (assuming they are still listed in a role on the parent).