Classic video. Woodstock, and that performance of "Soul Sacrifice" in particular, was really Santana's big break. At the time, they hadn't even released their first album yet -- the only reason they got to play Woodstock was because Bill Graham (one of their early supporters) used his influence to get them on the bill. "Soul Sacrifice" made it onto the Woodstock movie and the soundtrack album, and the rest is history.
By the way, the bassist in that clip is David Brown, and he's part of the Santana lineup that got inducted into the Rock & Roll Hall of Fame.