Planxty was, along with the Bothy Band (see also here), one of my favorite traditional Irish groups. I never saw any version of the whole group perform live, though I did see Paul Brady and Andy Irvine, sort of a rump Planxty, at Town Hall in the early 1980s, and, since my date knew them, got to meet them backstage. In the late 80s I saw Andy performing solo at the Eagle Tavern, and, since my date (not the same one as at Town Hall) knew him, got to have a beer with him after.
Some time ago I posted a YouTube clip of Planxty doing "The Jolly Beggar". Unfortunately, that clip is no longer available, but I've found another of the same 1980 lineup: Donal Lunny on bouzouki (a Greek instrument which Andy, following Johnny Moynihan, championed the use of in Irish music), Andy Irvine on mandolin and lead vocal, Liam O'Flynn on Uilleann pipes, and Christy Moore (who introduces the song) on guitar, doing a sea chantey, "Sally Brown", first made popular by Sweeney's Men:
I also found a clip of a different, 1974, lineup, with Irvine, Moore (who here plays bodhran), O'Flynn, Paul Brady on guitar, and Johnny Moynihan on fiddle and lead vocal, doing one of my favorite Planxty numbers, "The Frost is All Over":