I finally found the video shot by the WB-57 chase plane of the ST-114 "Return to Flight" launch. It's fabulous. Keep watching, and near the end you'll see the SRB seperation. The plumes from the seperation rockets are huge!
NASA article on the development of the WB-57 camera system
I think this is really compelling imagery, but it's grainy and shaky. Still, it's way more interesting that the view of the three white dots of the engines during ascent. A little postproduction work could stabilize the imagery on this video, and yield something even more fun to watch.