1) That info is also available in 'DGMPEGDec 1.0.13 beta 11'. Using
mpeg2source(info=true)
2) Use latest beta of GSpot and look in the upper right corner. In the video section, the five boxes next to NVOP. The fives boxes are from left to right:
1) I709 (= Rec.709 coefficients)
2) FCC (almost the same as Rec.601)
3) I470 (= Rec.601 coefficients [an updated version of Rec.470-6, but coefficients are exactly the same])
4) S170 (= SMPTE 170M; exactly the same as Rec.601)
5) S240 (= SMPTE 240M; almost the same as Rec.709)
see table 6-9 page 56 of
http://le-hacker.org/hacks/mpeg-drafts/is138182.pdf
If the boxes remain "black" then the used coefficients are not present in the header, and the default (which is Rec.709) should be assumed.
I hope it's clear now