Which app to watch movies?

[bsdnooby]

I'm trying to watch some movies from archive.org, but I'm not familiar 
with the correct process.  I installed xine and avifiles, but they can't 
play the free mpeg4 movies I'm downloading from archive.org. 

Am I supposed to install the codecs separately?  Or should I be using a 
different video player?  I'm not clear on what the relationship is 
between the various players and codec packages in /usr/ports is.

Other than xine, I'm not sure which other ones are most commonly used.  
I'm trying to watch some of these movies:

http://www.archive.org/movies/movies-details-db.php?collection=prelinger&collectionid=17225&from=mostViewed

Any movie watching tips would also be appreciated.  Oh, I did get 
Realplayer8 to work inside WINE, which was pretty cool.

thx!