One thing I wish you could do is have two different copies of an input - in my case, I wanted a video stream input (webcam) where I apply one set of filters to it for one scene, and a different set of filters to another scene. Seems like filters are globally applied to the instance, and you can't have two different scene elements with the same video input device.
You can use groups to accomplish this currently, but it's not the most obvious thing. Just create two groups, and add the shared source to each group, then apply your filter to the group itself. Scene-specific filters and other scene-specific features is something that is on our to-do list, but very tricky at best.
