Can we fulfill the law just by being commanded to love?
No. While Paul says that loving one another fulfills the whole law, he defines love as seeking the other person's highest good, not as mere command-following. The context states we cannot do this simply on the basis of commanding; the command alone does not produce the love that fulfills the law.
Les explains that the love Paul speaks of is not erotic love or Hollywood's idea of love; it is a love that seeks the other person's highest good. If a young man dating a girl, a husband and wife, or a neighbor each seek the other's highest good, Paul says they are fulfilling the whole law. But Les emphasizes that we can do none of this just simply on the basis of commanding, because we never really grow up.