Open Youtube using your browser. Copy the URL of the Youtube video you want to convert to MP4 and save it to your clipboard.
Copy the URL of the video you want to search into YtMP4. Tap the red button and it will open the search box. To search for videos on Youtube, you can also enter keywords.
Next, select the file format that you want to download and then click "Get Link". You can then download the file by clicking on the link.
Select the right-click menu item 'Save as', and then enter the file name. Have fun!