S.U.P.E.R encoder problem

[varunb]

I encoded an uncompressed YV12 AVI to Quicktime H.264 file using S.U.P.E.R encoder. On viewing the output I noticed that in the beginning of the playback, there's a lot of brightness which reduces automatically. I have uploaded the sample here:

http://www.sendmefile.com/00511100

I have tried almost every option in the encoder(tried the directshow option -> no reduction in luma) still, i am not able to remove that high brightness that occurs. Need suggestions guys...