why are *.avi movies shown when PgDown and PgUp ?

[pstein]

I have a folder with 4 files:
2 pictures (*.png and *.jpg)
and 2 *.avi videos

Now I open one of the pictures.

When I press the keys PgUp or PgDown then 4/4 is displayed in the status bar.
And when I PgDown then the *.avi files are tried to displayed as well (currently as black pane).

Why?

In menu

Options->System integration->Associations

the extension

.avi

is disabled (unchecked) resp. not listed.
Similarly in menu

options->Browser->File list

only Images and Folders are checked. Not video files

So *.avis should not be listed.

What's wrong?