I just saw the clip and song by Joe Raposo "I'm in love with you pretty baby" with the two rhinos. It's been quite a long time since I've seen it but I remember it being shown a ton of times in the early to mid 70's. The uploaded clip is missing the last 20 seconds or so of the clip which Joe ended by saying, "And if some day my dreams will all come true, there'll be another pretty baby like you."
By the way, does anyone know if Joe Raposo songs like this one, "Fancy", and "I love your funny face" were all his original lyrics or if some were actual old songs that he sang his version of, accompanied by the animal visual footage. I think they all were probably his own lyrics.