Comment 20 for bug 520941

Looks to me as though there's a mismatch (off by 1) in the sequence.mlt between the start of the transition and the start of the video. I think the video is starting 1 frame before the fade in, so we end up with 1 frame of full brightness. If you move the offending clip to a different timeline then the clip-transition timings match and all is ok.

Haven't had a look in the code at what's causing this yet.