Stevie Ray knew what he was capable of doing when he played .. he was a beast on the guitar. Growing up he had many blues guitar hero's but Albert King was in his top 5. Out of total respect and sheer love he had for Albert (frankly, all blues artists SRV jammed w/on stage) Stevie would pull back and not go 'beast mode' on the guitar in order to not outshine his guest. The moment wasn't about him. It was just about having a good time doing what he and Albert loved to do .. Make beautiful music together while playing the blues.
When you get I chance watch the whole performance, it's over an hour, it was recorded for a TV show. The relationship between these two was a beautiful thing. Stevie loved & admired his hero Albert King & Albert felt the same about Stevie after meeting him several years earlier. They stayed close until Stevie's passing. Also there's some really heartfelt chatter between the two during the show.