Most videos of Stevie Ray Vaughan show him performing on the electric guitar. There are fewer examples of him playing acoustic, and the video shown here is certainly among the earliest in existence.
In it, Stevie is playing alone on a battered vintage Gibson acoustic guitar, giving the instrument a solid workout as he burns through an improvised 12-bar blues.
This video appears to be a clip from a 1983 interview on a Dallas, Texas, radio station. Vaughan was still new to audiences at the time (his debut, Texas Flood, came out in June of that year), and the clip begins with a snippet of him telling the radio audience a bit about himself and his background.