thumbnail and aspect ratios

hi,

i’m having problems with none-320×240 flv videos (no youtube, uploaded only) that i’ve encoded, specifically stuff that’s in a 16:9 aspect ratio (pixel dimensions of the flv are 426×240). actually the flv itself plays just fine, both in stretched to fit and uniform modes. however, the thumbnail simply doesn’t display and i get a black rectangle instead. this does not happen with my 320×240 thumbnails. the problem is not related to short codes or anything (although i tried), because the rectangle is already black in the wordtube media manager page of the wp admin interface. my playlist shows thumbnails for all 320×240 videos while my 426×240 ones are black (but, again, play just fine).

i tried creating 320×240 thumbnails for the 16:9 videos by cropping them but even that doesn’t work. does the flash player dislike 16:9 videos/thumbnails altogether?

thanks for any help.