Here's a 9-minute video on YouTube that reviews the arguments on both sides of the issue. The description of the video reads:
Winters have heated up in Yellowstone as the controversy over snowmobiling has reached the national stage. Park ranger Mike Yochim offers a summary of the arguments, while two residents of West Yellowstone, opponents on the issue, speak out. Produced by Elliott Kennerson, 2008.
Great issue. Michael Yochim, the NPS ranger who put the video together, later wrote a book about the issue, Yellowstone and the Snowmobile: Locking Horns Over National Park Use (Univ. Kansas Pr., 2009).