You need a capture card of some sort. Those files on the SD card aren't useful as replays. The images are useable and I think they've made strides with interpreting level editor files, however the general consensus is that video files from SD cards are only viewable on a Wii with Brawl.
The reason for this is that the replays simply record your button presses throughout a match up to 3 minutes in length. There is no video stored because that would require an incredible amount of storage as well as a long amount of time to compress/write. If the files were video you wouldn't be able to rotate the camera around when you pause the replay.
Check out this thread for in depth info:
http://smashboards.com/showthread.php?t=142971
(Thread on cracking screen cap files)
Your best bet may be to send a replay file to someone who has a capture device. There are also threads about cheap capture devices, sub $70 US, so poke around in this video thread too:
http://smashboards.com/forumdisplay.php?f=109
(Video thread)