I think ER relies heavily on steadicam movements. (I'm not a regular viewer of the show but I know what scenes your talking about.)
Everyone volunteered for the project. I have to give MAD PROPS to everyone that was involved. It was all created for the 48 Hour Film project this past summer. Basically it is a competition where teams have 48 hours to write, shoot, and edit a film. No preproduction work can be done (other than locking down equipment, locations, cast, and crew) Then each team has to draw a genre of a movie out of a hat and they are stuck to make a film in that style. I have always wanted to do a one take film so I figured, why not give it a shot. It was great to know that when we got done shooting I didn't have to rush off to the edit room. Actually got a bit of sleep this year. It was definitely a fun time though.
Back to your first message. You can check out some shots of the steadicam here: http://www.flickr.com/photos/scott_regan/1488260858/in/photostream/
Its a rig that has a vest that you wear. Off that it has an arm that holds the weight of the camera which is balanced by the rod it is held on. Its a very fun toy. I love to shoot with them whenever I can.