When I use the "Add folder" button under Options / Thumbnails / Cache, the movie files are ignored. It would be great if they were processed too. Didn't test with all extensions, but at least the *.mts ones are.
(Initially it also appeared to ignore the thumbnail quality setting, but on closer inspection it turned out that "Lossy High Quality" actually results in very significant JPEG artifacts - but only once you've switched away and back. I have disabled "use embedded thumbnails".)
XnView 1.99.5 on Win7 64-bit.
Thumbnails / Cache / "Add folder" ignores video files
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