Tomas Gonzalez-Torres, the Discovery mission's lead spacewalk officer, explains what will happen during the first spacewalk of STS-121. Spacewalkers Mike Fossum and Piers Sellers will test whether the 50-foot inspection boom carried on the shuttle could be used as a work platform for repairing the heatshield and conduct maintenance chores outside the space station.
Source: NASA TV (8 min 57 sec QuickTime 6 file)
Download this clip to your hardrive.
(Windows users right-click this link. Mac users control-click this link)