As I mentioned in my comment above, the window is a "tool window", which
is intended to be used as a floating toolbar. A tool window has a title bar that is shorter than a normal title bar, and the window title is drawn using a smaller font. A tool window does not appear in the taskbar or in the dialog that appears when the user presses ALT+TAB.
For some reason, a few VLC Media Player windows appear as tool windows that don't have focus. There doesn't seem to be a way to activate them with the keyboard without using some helper program.
One possible solution is to find an Alt+Tab replacement that will list tool windows. I found an AutoHotkey script that might work, but will require you to install AutoHotkey and modify a script. Here are the steps involved:
- Download and install AutoHotkey.
- Go to Alt-Tab replacement and save the AltTab.ahk file.
- Open the AltTab.ahk file in Notepad.
Find the following text in the file and delete it.
If (((es & WS_EX_TOOLWINDOW) and !(Parent))
or ( !(es & WS_EX_APPWINDOW)
and (((Parent) and ((Style_parent & WS_DISABLED) =0))
or ((Owner) and ((Style_Owner & WS_DISABLED) =0)))))
continue
Save the file.
- Put the AltTab.ahk file in a folder somewhere. (It will make a settings file when you run it.)
- Make a shortcut to AltTab.ahk on the desktop or Start menu or Startup folder.
After the modified AltTab.ahk script is run, pressing Alt+Tab will bring up a new window switcher that lists tool windows. Here is what it looks like:

Ideally, VLC Media Player should be updated to either not use tool windows, or at least give them focus. You or your friend might try discussing the problem on the VideoLAN forums, perhaps other users have found better workarounds or solutions. For example, I found the following threads that report the same issue with the "Go To Time" box and show a bug report has been filed: