The UtVideo RGB file of that scene worked fine on my end. I played it back using LAV Filters with MadVR in MPC-HC. I then encoded the sample to x264 using ConverttoYV12(matrix="rec.709") and the colors stayed exactly the same, no reds that turned into orange. Here's a link. You can check it yourselves.

https://rapidshare.com/files/671478413/Leia-RGB-sample_colorfix.mkv

Harmy, if you want render said scene to UtVideo YUV420, upload it and I'll check if everything is fine.

Usually decoders decide which colorspace to use based on the resolution of the video, which should be fine. So I think the renderer messes something up here.