Go to the athlete's profile page and scroll down to their "Video" panel.  You may scroll through the video thumbnails on the left side of the panel and on the right side, the video will play inside the panel.

This will show you all of the videos featuring this athlete.

To Add a new video of an athlete, use the Share button on the left-side menu and select Video:

Once you select type of video content you have to add (either by uploading image or video from your computer or by linking to an uploaded video from youtube).

Then you can use the "Featuring" tool on the right side to find and tag and the new video with the athlete's name.  

Any videos tagged with an athlete's name will now appear in their "Video" panel described above.