An archived forum thread post suggests the ACC library can do that.
I also found the ACC library helper tool called Accessible Info Viewer .
I drag the "cross" in the info viewer onto the VLC window duration text element (the text in red box here http://i.imgur.com/rbNkF6T.png ).
This information is then shown in the info viewer: http://i.imgur.com/ZLlKIx2.png
The data I want is called Name in the info viewer, "1:57:02" in this example
But I've so far failed to make a small script with acc.ahk to read that into a variable for use in the script.
I've tried the below and a few more variations. But I probably misunderstand something about the syntax for the Acc_Get command. Help!
;test := Acc_Get(Cmd, ChildPath="", ChildID=0, WinTitle="", WinText="", ExcludeTitle="", ExcludeText="")
test1 := Acc_Get("Name","3",0, "ahk_class QWidget5") ;test = nothing
test2 := Acc_Get("Name","3",0, "ahk_exe vlc.exe") ;test = Application
test3 := Acc_Get("Name",3,0, "ahk_id 0x480AEC") ;test = Application