I beleive its "tao" Seegers son in law playing guitar + you can just the back of pete's head in a wool red cap, marching in front. Singers in second video include, Arlo Guthrie David Crosby, David Amram

second video has " we shall overcome"
http://www.youtube.com/edit?video_referrer=watch&video_id=973-y_wKEOg