Stray Dog is a hard rock power trio from the early 70s, led by Snuffy Walden (who is mostly known for scores for various television shows).
These are videos from concerts where Stray Dog played, so they may be of other bands that played the concert as well.
Audio recording of first half of ELP Performance
Emerson, Lake & Palmer / Stray Dog Nov 15, 1973 Miami, Florida, United States Added by Grantv