Khan Academy on a Stick
Primeros seres vivos terrestres
Primeros seres vivos terrestres (este video registrado bajo licencia de Commons Attribution y Share-Alike CC-BY-SA)
If the above player doesn't work, you can try this direct link.
Primeros seres vivos terrestres (este video registrado bajo licencia de Commons Attribution y Share-Alike CC-BY-SA)
If the above player doesn't work, you can try this direct link.