You do know this is a 10 dollar script? I think you have 2 choices pay 400 dollars for a better known script or (i like this one better) buy this script and pay someone to mod the couple of features this script doesnt have that you need.
As far as i know these things in your needs list are suitable:

1. Yes you can make it so you are the only ones to upload to it.
2. You can set your server and the script up to cater for 1-2hr videos (if your server is powerful enough)

3. You may have to pay someone to set up a pay per view basis, but it wouldnt take alot to mod the current script.
4. FLV videos flash is multi operating system.
5. Yes it does have paypal, and normal paypal u pay straight into it with your credit card.

Hope i answered your enquiries (Im not a part of the script team, but i do love the script) good 10 bucks spent.