VMD is a versatile molecular visualization program. It is very good at displaying MD trajectories and is geared towards biopolymers and liquids but it can be used for a wide range of systems.
On the Macs, you will find it in /Applications.
Example (AdK) below was rendered with Tachyon (internal) with VDW representation, colors silver, yellow, and blue, no depth cueing, material AOChalky, and using Ambient Occlusion (AO) and Shadows (see Display → Displaysettin)
Note that you probably need to set your PATH in your ~/.profile file and completely log out and log in so that VMD will find your own ~/bin/ffmpeg binary)
You can view mpeg-1 movies simply with
MPEG-2 is better quality but Apple's QuickTime player seems to have a hard time decoding it... Linux programs tend to do better here.