You can select (highlight) items in the remote, local, or queue pane by name or type using Group Select and wildcard masks.
Click in the pane where the files exist.
On the menu bar, click Edit > Group Select.
In the Select group box, type *. and then the extension for the file type you want to select.
Clear the Mask Folders check box to exclude folders from the selection.
Click OK.
On the menu bar, click Edit > Invert Selection.
With files highlighted, click Edit > Group Deselect on the menu bar.
In the Deselect group box type the name of the file you want to deselect, or use wildcard masks to deselect a group of items.
Select Mask folders to include folders in the action.
Click OK.