Is it possible to create a single room or window where only a few selective accounts will be displayed?

I am not sure about your meaning of "room", "window" and "accounts".  Most users only have one account. But you can become a group account. The Group Account service is designed for Resellers, but it can also be used for enterprise customers (or customers with many cameras). 

You can log on to www.cameraftp.com website, go to My Account page, click on Group Account. Then upgrade to a group account (for free). You can then create sub-users.

If you want a sub-user to be able to view certain camera(s), you can share the camera(s) with the sub-user. You can share different cameras with different sub-users.  Sub-users can only see the cameras shared to them.

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Alternatively, a reseller (the group owner) can log on as a sub-user (from the Group Admin page), then order a subscription for the sub-user. The service fee will be charged to the group owner. You can add new cameras to the sub-account. This way, a sub-user can view and manage cameras in his own account.