Every Draft - Filter has an Input type. 

The Input Type is solely used to tell the Media Manager and Video Portal how to gather input from a user. If a Draft - Filter is not a Visible filter, then the Input type is irrelevant.

The Input Type of a filter is defined during creation of a filter:

Creation of a filter.

It can be edited in the The Details panel.

There are seven different Input Types.

string

Media Manager and Video Portal will display a text field to gather the user's input.

bool

Media Manager and Video Portal will display a combo box with two values: "true" and "false". 

datebetween

Media Manager and Video Portal will display 2 date pickers.

combo

Media Manager and Video Portal will display a combo box with 1-many values, from which the user can select a single value

multicombo

The same as combo, but the user can select multiple values.

assettype

Media Manager and Video Portal will display a combo box with asset types ("image", "video", etc) from which the user can select multiple values.

tree

Media Manager and Video Portal will display a tree structure from which the user can select multiple values.