Or, at least, Petrucci and Portnoy jamming with them.
This was from the tour where I Mother Earth opened for DT back in 1994 I think it was.
Also, this is with I Mother Earth's original singer, Edwin, who wasn't great, and still isn't
The DT guys come out at 2:20 after the guitar-slap bit. Portnoy does a pretty decent job of jamming out on percussion with the band, Petrucci gets into the mix at about 5:00 when they finally get him through a working amp and in the PA The second video's where most of the interesting stuff is.
[VIDEO]http://www.youtube.com/watch?v=7T0OFCrfiO8]YouTube - I Mother Earth - Rain Will Fall w/ Dream Theater Part1[/VIDEO]
[VIDEO]http://www.youtube.com/watch?v=ZCrpKRgTvRg]YouTube - I Mother Earth - Rain Will Fall w/ Dream Theater Part2[/VIDEO]