That depends on what video files you are using. The E10 supports only AVI format videos and to a certain extent, videos made on Macromedia Flash, though this may sometimes freeze up the E10 since the player is made for playing Macromedia games, not videos.

To test your E10, download a few movie clips from the iriver site here*.

Next, connect your E10 to your computer and drag-and-drop the movie file into the video folder of your E10. Disconnect your E10, go to the video option, and you should see the name of the movie file listed there. Play it. If your E10 doesn't, something's obviously wrong. Bring it back to iriver for a checkup.

*Some videos would have either the prefix (E10) or (U10). It simply means the video has been configured to fit either the E10 or the U10's display. For testing purpose, either type should work fine.