1080p60 video playback stutter, judder, frame drops

I am experiencing frequent, random video frame drop, and perhaps stutter or judder when playing (28Mbps) 1080p60 AVCHD clips in VLC, Movist, Toast Video Player, and QuickTime player. The video jumps occur at different spots in the clip and sometimes not at all, so I am reasonably sure the source clip is clean. I am viewing at the default size in each player, so the issue is not from scaling to full screen.

Clip I am using is at: http://dl.dropbox.com/u/65146689/TrafficTripod_f3p2_ISO100.MTS

Movist crashed twice playing the video with the following msg:

Exception Type: EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000000000000
Crashed Thread: 3

Thread 3 Crashed:
0 com.cocoable.Movist 0x002ac39a libebml::EbmlSemanticContext::EbmlSemanticContext(unsigned int, libebml::EbmlSemantic const*, libebml::EbmlSemanticContext const*, libebml::EbmlSemanticContext const& (*)(), libebml::EbmlCallbacks const*) + 2735750

iMovie crashed on QT x264 59.94fps export a couple times as well (source processed by ffmpeg to ProRes422 for input to iMovie).

It does not appear to be related to the bit rate, as the clip converted to ProRes422 has a 255Mbps rate played in QT player will sometimes drop frames or stutter, but no more than the 28Mbps clip and sometimes without a single problem.

I am running Snow Leopard 10.6.8 on a 2009 iMac11,1 with Core i5 2.66GHz processor, 8GB ram, ATI Radeon 4850 512MB graphics card. When the clip is playing, Activity Monitor shows all four cores at reasonably low usage with no high peaks.

Any Ideas how to clean this up?