One of Hayao Miyazaki's earliest works (he was a "scene designer," an apparently made-up position used to give him credit for an inordinate amount of influence), Horus: Prince of the Sun is a wonderfully simple fable of a young man/boy (boyman... manchild?) fighting a demon.
Remember, this movie was from 1968, and Japanese animation was not the juggernaut that it is today. Quality was usually very poor, and storylines, far from the adult-oriented works of today, were aimed primarily at children. The animation work in Horus, while not up to Disney-snuff, is still very solid, expressive, and honestly, better than most of the stuff being made in Japan today.
At times, the movie is hilariously Japanese (really? We're going to break into song again?) and the trope of a demure female who has a magical voice is in full force (I'd love to see her in a cage match against the two midget babes that summon Mothra).
Still, the character of Hilda is much more interesting than many females in Japanese movies, and serves as a sort of preview to the powerful women that will populate Miyazaki's work over the next four decades. She's most like Sheeta, from Castle in the Sky, in that she's magical, quiet, and frankly, a little bit useless. Horus is also very much like Pazu (or Paizu as the American version sounds) in that he's incredibly capable, adult in almost every way but appearance, and wholly dedicated to protecting Hilda.
Set aside 90 minutes and enjoy some of the best early anime I've ever seen.
If you're watching on a big screen, which is best, make sure to select 480p on the parts that allow it.
Are you fucking kidding me?! Taken down because of a copyright claim. It's a 42-year-old cartoon that NO ONE except me and, like, three other people give a shit about. Go fuck yourselves, TOEI.
I've re-posted another upload of the film. If it gets taken down again, I'll track down another copy and post it. If it's not available still, go download Vuze, hit up Isohunt.com, and download it yourself. Then you'll have the whole thing in high quality and TOEI will have lost ANY chance of making money. Brilliant business strategy.
UPDATE 8/29/2010: AGAIN... TOEI has had the Youtube videos taken down. The NANOSECOND that they are available again I will post them. I am so fucking pissed.
For now, the video is available on Hulu, which I'm embedding, but its dubbed, adequately, and the video is somehow of lower quality than the Youtube copy. It gets the job done, but the original Japanese sounds betters. And for some reason is called "Little Norse Prince Valiant," which doesn't actually make sense.
I said it before and I'll say it again, TOEI can go fuck itself.
UPDATE 11/28/2010: Got it.
Here's the HULU copy in English dubbing.