There's a chance they could've been using a Dreamcast emulator on Chankast, you can find those over at dcemulation.com. But they may have also been running the Sega Smash Pack Volume 1. I beleive that compilation includes Streets of Rage 2.
basically yes, the emulator is a hacked version of the segasmash pack, where you can add your own games to it, but i cannot give any details of it, because its quite dodgy