If you want to upload video directly form your iPhone to YouTube, there is an option do that. Follow the given instructions to upload videos to YouTube form iPhone 4 or 3GS.
How to upload iPhone video to YouTube
Note: Make sure your video is no longer than 15 minutes.
Step-1
Create an account on YouTube if you don’t have one.
Step-2
On your iPhone tap 
icon while viewing video and then tap “Send to YouTube”.
Step-3
Log in to your YouTube account.
Step-4
Enter video information Title, Desc, etc.
Step-5
Tap Category to choose the right category and then tap publish.
See also:
thanks for iphone 4 tips
how do i upload a video that is longer the 15min from my iphone?
Hi,
To upload video on YouTube longer than 15 minutes, please follow this link https://youtube.com/my_videos_upload and click the increase your limit link.