Here's a really great video of an awesome Zeppelin song. Jimmy Page really shows his brilliance as a guitarist right from the start, and Robert Plant really brings out the dramatic side of the song, both with his vocal performance and stage presence.
As an improvisational showcase for all four group members, and especially for Jimmy Page's electric blues guitar solos, "Since I've Been Loving You" became a staple and fan favourite of Led Zeppelin's live concert performances from 1970 until the end of their ninth American tour in summer 1973. It was played on the 1970, 1971, 1972, 1973, 1977, 1979 and 1980 tours, but only a few times on the 1975 North American tour. In live performances of the song from 1977 onwards, Page would sometimes incorporate some of the solo of "Tea for One", a track from the band's 1976 album Presence that is similar in style to this song.
Page's guitar prowess is well demonstrated in different performances of the song from Madison Square Garden in July 1973, as seen in the group's concert films The Song Remains the Same (and accompanying soundtrack) and Led Zeppelin DVD.