Story 3 - episode 14

¿Qué necesita hacer el mono?

Episode 14:

Episode 14 with pop-ups:

Additional follow-up questions:

1. Look at the following phrases:

• El mono y el pollo corren del león.
• El mono necesita saltar en la cama.
• El mono necesita saltar de la cama.
• El elefante salta del árbol.

Why does the third one say "necesita saltar de"?  Why does the fourth one say "salta del árbol"? 

What do you think "de" and "del" mean there?

2. If "necesita saltar de la cama" means "s/he needs to jump off the bed", why does the elephant say , "Necesitas saltar de la cama" to the monkey?  Why is there an "s" on the end of "necesita"?