rewind2 can't get past a frame

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I've set the medium jump (rewind2/forward2) to 10 sec. On many AVI files when I medium-jump backward it works a few times, but then I get stuck on a specific frame, unable to go beyond it (as if the frame was some kind of "chapter break" or a "keyframe"). Clicking the slider on a position before that frame works fine. Is there a way to fix this?

I'm on Win7 x64, SMplayer 0.6.9 (SVN r3447)
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