on open these_items
    repeat with i from 1 to the count of these_items
        set this_item to item i of these_items
        set the item_info to info for this_item without size
        set theName to name of item_info
        try
            set theExtension to the name extension of item_info
        on error
            set theExtension to ""
        end try

        if theName contains "thumb" then
            tell application "VLC"
                activate
                open this_item
            end tell
        else if theExtension contains "jpeg" then
            tell application "Preview"
                activate
                open this_item
            end tell
        else
            -- open with system default app
            tell application "Finder" to open this_item
        end if
    end repeat
end open