To play YouTube Videos on iPhone 4, you have to convert the downloaded YouTube videos to iPhone 4 supported format first. Because the downloaded YouTube videos (FLV videos) can not be played in iPhone 4 yet as iPhone 4 supports to play videos in MP4, not FLV.
Cucusoft DVD to iPhone 4 Converter Suite should be your good assistant to help you convert YouTube videos to iPhone 4. It is the most powerful and efficient YouTube video to iPhone 4 converter that can convert YouTube to video to iPhone 4 supported formats. In addition to the primary function to convert YouTube video to iPhone, this iPhone 4 Converter Suite can also help you to edit videos by trimming, cropping, and adding logos over the video.
This guide shows you the exceptionally easy way to convert YouTube video to iPhone 4 with Cucusoft DVD to iPhone 4 Converter Suite, then you can play YouTube videos on iPhone 4 freely!
Tips: This program is for Windows user. If you are a Mac user, here is iPhone 4 Converter for Mac>>
Step 1: Run iPhone Video Vonverter and then click "Open file" to open the YouTube video files.

Step 2: Click "Profile" to set the output format as iPhone 4 MP4:

Step 3: Click "Convert" to convert YouTube video to iPhone 4 MP4 format. Then sync the converted files to iPhone 4, Done!
Free downlaod iPhone 4 Converter Suite to convert YouTube video to iPhone 4 MP4 format so that you can paly YouTube videos on iPhone 4 as you like! For Mac user, please free downlaod this iPhone 4 Converter Mac to help you paly YouTube videos on iPhone 4.
Related: How to Convert MKV to iPhone 4, Convert DVD to MP4 with H.264