Found this one:

The mag prints were used for the DVD audio.
Oh crap! …Did I write that? [IMG] After reading a few
posts afterwards, I decided to revisit the various video
versions of Forbidden Planet.
At one time or another I’ve either owned or have been able
to borrow from friends almost every LD/DVD version of
Forbidden Planet available in the US. I’ve watched the
first pan-n-scan laserdisc, which Doug Pratt claimed was
missing the surround tracks. Was Doug Pratt right? I don’t
know, but it wouldn’t surprise me, with the attention
stereo soundtracks received from the studios at that time
period. That disc went by “bye bye” when a friend acquired
the Criterion CAV letterboxed edition. (One of the FIRST
letterboxed LDs) Later there came the cheaper MGM CLV
version, (didn’t get to see the MGM CAV version) then
the MGM DVD, folled by the Warner Brothers DVD. My friend
no longer has the Criterion version nor do I own the CLV
MGM LD, but I did make VHS hi-fi copies of both way back
when, which allowed me to make a recent comparison of the
stereo mixes of the three video versions. …Now before
someone balks at VHS hi-fi, allow me to point out that VHS
hi-fi has phase error and channel separation specs equal to
most consumer digital formats. Yes, VHS hi-fi does suffer
in other areas, but these two specs ensure stereo and
matrix surround audio are played back properly. Those two
specs are the one’s important for these reviews, but if
someone wants to do a follow-up with the original LDs,
I’m all for it!
I tested three segments of the film in an A/B/C review fashion:

Opening narration with music right after opening credits.
Roughly 17 minutes into the film, Dr. Morbius has Robby
show off the household disinegrator beam.
Roughly 20 minutes into the film, a protective shell
consisting of panels is put up around the house.
The opening narration highlights the differences in the
audio transfers quite nicely. On the Criterion version,
the announcer remains anchored in the center channel,
while stereo synth music gently spreads to the left and
right speakers. But the MGM version has the announcer in
all three front speakers, along with the stereo music.
The WB DVD keeps most of the dialog centered but with
no perceptible stereo music.
This makes me wonder if the MGM LD had slight phase errors
during the mag audio transfer, which would effect the
perceived stereo spread. The MGM LD’s audio is clean, and
the stereo is intact… but it lacks the center channel lock
that the Criterion version offers. This difference is
later heard during the various slight directional dialog
pans throughout the film. The Criterion transfer tracks
these pans slightly better, while the MGM LD pans seem to
“pop around” a smidgen more when Pro-Logic decoded, which
again could be due to a slight phase shift. …The WB DVD
simply has NO directional dialog.
The Desinigrator Beam sequence has Morbius activating the
beam briefly (leaning towards the right channel.) …Then
there’s the securing the house sequence a few minutes
later. This “closing panel” pan starts at the right and
ends close to the center channel. Both the MGM and
Criterion LD both have the same effect. The WB DVD version
is flat mono.
So is the WB DVD completely mono? During music passages the
audio seems to spread out over the three channels some, but
nothing that screams out true stereophonic sound. I was
able to check out the WB DVD from my local library, and
this disc was slightly remade by WB after they acquired the
rights from MGM. (The disc opens with the WB logo.) …But
does the first MGM DVD have the original stereo sound? I
don’t know. In either case, I would have to give a NOT
recommended review of the WB DVD version, due to the
missing original stereo mix.

http://www.hometheaterforum.com/community/threads/forbidden-planet-se.41960/page-2

Digging around the HTF reveals manyhreads with complaints about the old DVD and how it pales in both color and sound to its LD source.