On AWS, bandwidth costs as little as $0.08 per GB and storage costs as little as $0.055 per GB. Are there any providers that charge less? These numbers end up being very costly for a web site that hosts pictures and videos, so I'm looking for cheaper alternatives.
Here's a site that compares a few cloud hosts, although I'm not sure how up-to-date it is: http://www.mrkirkland.com/cloud-computing-price-comparison/
I also compared aws pricing to google app engine, and it seems that yes, aws is the cheapest.
However, you should also read about the quality of aws hosting before you use it, as I have heard of many issues from people using them.
Also, if you are looking into hosting pictures and videos, you may want to try to find a specialized host that serves images, and one that serves videos as a side-service in addition to hosting. They may have cheaper storage costs and better/faster distribution of the content.
There is also a site which calculates cloud hosting prices from various providers - www.cloudorado.com. You can just check how much would cost a server you need from various providers. Amazon is often not the cheapest unless micro instance is used.
Update: Here is also an article which tries to answer exactly the same question.
AWS gives you a virtual server all to yourself. If you just want to host pictures and videos then look for "shared hosting". You'll need to estimate your expected bandwidth and disk usage as many put limits, but often they allow you to buy extra.
You can find hosting with "unlimited" bandwidth and disk usage, but there may be a limit on the number of files you can have, or some fair use policy so that bandwidth isn't really unlimited, or may be shared with many other people, so gets quite slow.