Step 1: Download YouTube to H.264 software. Install and launch it.
Step 2: Download YouTube Videos and save YouTube flv to your personal computer:

Step 3: Convert YouTube flv videos to H.264 MPEG4 AVC(h264) video formats:
Click
to input YouTube video file to be convertered (batch convertsion supported, you can add as many YouTube files as you want).
Profiles option, you can choose "H.264 Movie (.mp4)" formats you want to convert YouTube to H.264 MPEG-4 AVC Movie:

Then click the folder button, select the destination folder where you want the converted H.264 MPEG4 AVC(h264) video files to be stored.

Click
button to start converting YouTube to H.264 MPEG4 AVC(h264).
Ok! we have finished the whole process to convert YouTube to MPEG-4 AVC(h264). Enjoy the HD movie on your favorite devices ...