Remove borders around AVI video thumbnails?

Directory Opus shows all my 1920x1080 Full HD AVCHD video as great and clear 267x148 pixels thumbnails and without any border.

But it shows my 1024x768 AVI videos with a border looking like an old 35 mm film taking up some of the thumbnail space for these Windows 7 explorer looking borders. The DirOpus borders are different from the Windows 7 ones, though, by having 4 feed holes on the sides while WinExp have 7 holes
The AVI videos are MJPG 4:3 1024x768 at 2.103 Fps 1071 Kbps from our surveillance cameras.

How can I switch off these borders for the AVIs please?

Go to Preferences / Viewer / Viewer Plugins, configure the Movie plugin and you'll find an option in there.

(You might want to tell the plugin not to generate thumbnails at all, so Opus falls back on the same Windows Explorer thumbnails. But there's also an option to keep Opus making the thumbnails itself but without the sprocket holes.)

Thank you - it works precisely as I hoped.