I like this video a lot, both because it shows the lion in peril against the pack of hyenas but also because it shows that it only takes one additional lion to change the balance completely. When the second lion shows up around 2:50 the hyenas just disperse and don't even bother fighting.
The first lion seems in a bad shape, though. That being said, the video mentions that he strayed a bit from his family's territory. Which suggests that lions are not that safe alone.
In general, if you read about the savanna, the consensus seems to be lions and hyenas tend to avoid picking fair fights with the other, because both pose a serious danger. And lions very often steal hyena's kills, subverting the image from The Lion King.
Hyenas are very clever social animals and very good hunters. And very dangerous, too.
