Youtube to Mp3 can be converted with this website very easily . The steps to convert youtube mp3 is given above. Using which any youtube video can be converted to mp3
You can download MP4 by right clicking download button and choose "Save link as...". You can also download MP4 in playing page by pressing "Ctrl+S" keys at the same time. When using mobile phone, you can download the MP4 by long pressing the playing video.