Likely David Burnett, but possibly Robert Beck as well, and if so, probably shooting Type 55. However, most of his Speed Graphic work is editorial portraiture, not features.
Then again, it's not like it takes a rocket scientist to use one, so it could be anyone who is shooting a feature. It would have to be someone with some respect in the industry, and probably a history of published material using the same techniques, though...otherwise they would not let him shoot anything other than a highly competitive camera.
Also, I would be surprised if there were any pool photographers there, Phil. No one is going to share photos with other agencies at an event unless absolutely required due to an extremely limited number of billets and/or other restrictions. Pools occur when it is impossible to get any more than one, or perhaps a few, photographers in. Something like a media-blitzed court case would have a pool (can't have 50 photographers snapping away in court), but likely not a sporting event.
Was he using flashbulbs? Probably nothin' doing with available light and large format. Was he actually shooting the action? I doubt it, but if so, he was probably rigged to studio flash heads in the rafters.
