I was surprirsed to not find a link to this on the forums actually, so I'm going to post it myself.

A few years ago, shortly after the release of HALO, a group of people decided to make a movie using the HALO gameplay. They use a well thought out storyline (and it continues through all the episodes), a growing cast of characters (yet not too big), and the varied maps from the HALO world (mainly Bloodgulch/Quagulation). After the release of HALO 2, they moved onto that, which increased graphics and various options that were avaliable to them. And an amazing part - in the beginning part of HALO 2, they had it so models didn't look up and down when the person did. They added this so the RedvsBlue group could continue their videos.

Sadly, they've advanced their site ( www.redvsblue.com ) to only allow the downloads of the current season and a few exclusive other episodes. I couldn't find a great site that simply lists all the episodes, but you can download them all from here:
http://www.archive.org/details/RvB_E01
Just change the last two numbers to the episode you want (01-60).
You should be able to just google what you want and find it pretty easily though. There's also some PSAs (Public Service Announcement) videos that are hysterical. Especially the one about the internet.

If anyone has some better links for this, please post them. Otherwise, enjoy!!

PS: Each episode is roughly 5-8 minutes in length. And they are best watched in order, because it's a continuing storyline.