FroggerNG (2.06) is by far the most supportive of the two programs it supports the following media types:
Supported video codecs:
AVI/QT/ASF/OGG
DIVX (M$ Mpeg-4) v1, v2, v3
Angel Potion MPEG-4
Radius Cinepak
OpenDivx/Divx4.x/Divx5.x
Windows Media Video 7
Windows Media Video 8
ISO MPEG-4
XVID MPEG-4
CCITT H.263
Intel I.263
Several MPEG 'I Frame only' video codecs.
Sorenson Video (SVQ1)
Sorenson Video 3 (SVQ3)
Motion JPEG (MPJA, MJPB, Photo JPEG, Rainbow Runner, and other jpeg based codecs)
3ivx Mpeg-4
Intel Indeo 3.x
Apple Animation (RLE)
Microsoft RLE 8
Uncompressed RGB video
Microsoft Video 1
Apple Graphics (SMC)
Several uncompressed YUV formats
Huffman YUV
On2 VP3
RM
RV10
PSX Video v2 & v3
MPEG-1 and MPEG-2
RoQ Video
Supported audio codecs:
AVI/QT/ASF/OGG/WAV
MPEG Audio Layer I/II/III
DVIADPCM
MSADPCM
IMA4
GSM 6.10
PCM (8/16/24/32 bits)
TWOS/SOWT
a-Law
u-Law
MSN Audio
MACE 3:1/6:1
Vorbis
WMA 1/2
MPEG-4 AAC
RealAudio 1.0
RealAudio 2.0
XA Audio
RoQ Audio
As you can see Frogger has a huge list of support, Moovid hasn't got so many codecs to offer but is the fastest of the two. MooVid supports the following:
AVI and MOV files in a single executable.
QT streaming video (QT3+), and QT 64bit files.
INTEL INDEO 3.1 & 3.2 (IV31/IV32)
The information here is cut and paste from the docs so it should be pretty reliable...
MooVid as I mentioned before is the fastest decoder on my 060, but I guess if you have a PPC speed wouldn't be so much of a problem if you're just going to watch movies.
In short:
Frogger has the best support
MooVid has greatest speed (on my 060 anyway, don't know if anyone will say the opposite)
Hope this helps you out a bit.