*EDITED BY AUTHOR

Well the best answer for this would be DIY right, unless you do not have programming skills. I guess you could try fiverr or has @Weponz suggested freelancer programmers.

You can approach TalentsfromIndia.com . They are well-known for providing skilled, dedicated and expert yet affordable developers.

Omnie Solutions is best option for business application and standalone mobile application development.So you contact by india.sales@omniesolutions.com.
Thanks

If You want android app, try this "Appsgeyser".. can make your own app and customize some extent within minutes... just in 2 steps ,Very simple ..
But it will not look so professional

Depends on the simplicity of your app. You can even make it yourself reading a couple of tutorials or a software to help you.

try a freelance website, jobs listings ,,, rekrus.com, is a free one.

Look for freelancers. Most app right now are being developed compatible with iOS and Android.

Just as a side suggestion - you have to get very specific about precisely what you want before getting somebody else to do it. Do you know precisely how you'd like the user experience to work? For instance

a) What is the first screen the user sees
b) Any screens that are linked from there - what precisely will be on them
c) When you say 'download' videos - how does this work on an iPhone - to the best of my knowledge it is not possible to download media (MP3's, Videos, etc) to an iPhone since there is no facility for local storage. Perhaps you mean stream? I think this is pretty possible.

If you get all this stuff precisely worked out it will really help you get detailed and specific quotes.

In regards to selecting a freelancer - MAKE SURE you see work they have done before. If they don't have anything published on an appstore that you can verify do not work with them. Make sure you carefully look at the apps they have built before and make sure their quality meets your expectations.

As everyone suggested freelancing is good option.
If you want to try for yourself than first create a mobile website and make it into iphone APP.But i am not sure if the users may be able to upload data as it requires complicated coding.

Do you have any knowledge about application development? If you do, but you are not very sure about your skills, then you may do some extensive research on the Internet and find out about such sites, where you can find online training on such topics. This may help you to some extent.

However, in case you are not willing to go this way, then place ads on various freelancing sites. Here you will find a lot of professionals who can be of help to you. Their charges are also affordable. However, the main drawback of this is you do not know how skillful or experienced the professional is whom you decide to hire from such sites.

On the other hand, if you are willing to shell out come money, then the best option would be to hire a professional app developer. This will help you choose the best and also get the work done as per your requirement.

Hope my suggestions will help you with your decisions.

Graviity.comGraviity.com Makes awesome apps and mobile sites.

Send me a (PM) I've been able to build several applications, softwares for many warriors.

cheers!,
Guillermo-

Mail me if you are interested to work with us, we have experts in iPhone/Android/Windows Phone application development