You can download the videos by clicking on the down-pointing arrow to the right of the file name on the video player.

They are flv format. When we looked at all the formats available, flash video was the one we could expect most users to have, with no issue about viewer compatibility.

For a local player, you can get a free one for pc:
http://rivavx.com/index.php?id=422&L=3

For mac, I don't know if there is a free one.