Convert YouTube Video to MP4

I have a single YouTube link—http://www.youtube.com/watch?v=QX_oy9614HQ&start=0—that I need downloaded and converted to an MP4 file. The final file should be delivered in 480p resolution while retaining the original audio track exactly as it appears on YouTube; no trimming, subtitles, or other edits are required.

Please use reliable tools such as youtube-dl or ffmpeg (or any comparable workflow you trust) to ensure the video plays smoothly on standard media players. A quick turnaround is appreciated. Once complete, simply share the MP4 file via direct download link or attach it here, and I’ll confirm playback before releasing payment.