Playblast/Reference Viewer for Maya
The Playblast/Reference Viewer brings a compact, yet powerful, video player to the Maya toolset and includes a number of features specifically designed to assist with animating in Maya.
Highlights include syncing to the Maya timeline (with an optional frame offset), setting a custom frame range, to isolate specific areas of interest, and playback controls that allow for single frame stepping and mouse scrubbing.
Update: Keyframe MP: Playblast/Reference Viewer Redux (Vimeo)
This is an internal script and not available for download. See Keyframe MP for the public release.