This first one has a young Alfonso Riberio. He played the Michael Jackson allegory on Silver Spoons and taught us to dance with his immortal Breakin' and Poppin'. Later he was the uptight Carlton on Fresh Prince. Here he shows a good example of honesty in the face of an angry opera diva.
This one has no notable stars that I'm aware of, but predicts dire consequences for those who stretch the truth. Apparently once one lies, his brain will ache, his heart rate will increase and he'll wish death upon himself. Don't worry, kids; it gets easier the more you do it.
The PSAs were produced by the LDS Church (the Mormons). They always had a pretty big budget for glossy and well-made commercials. The message is good, if saccharine. To date the Mormons have never lied.