I checked C-SPAN's TV schedule also, but didn't find the Red Sox White House visit aired anywhere. I found the following info under "Today's Events" on the C-SPAN schedule, but it looks to me that C-SPAN aired (or taped footage) of a 5 minute speech by Pres. Bush, and that there is no C-SPAN video for sale:
Speech
Boston Red Sox Appearance
White House
Washington, District of Columbia (United States)
ID: 185729 - 03/02/2005 - 0:05 - No Sale
Bush, George W., President, United States
Oh well, that's the best I could come up with. Hope NESN airs it for us.