YouTube to MP4 is only for a public video you may save
Save an MP4 of a public YouTube video you have the right to keep.
Paste the link and download an MP4 when the stream can be fetched.
The link leaves your browser
Only content you own or are allowed to download. Live streams and private videos will not work. Expect occasional failures when YouTube changes access rules.
Details are in the privacy policy.
Why YouTube to MP4 is its own job
YouTube to MP4 sits on this site because YouTube and MP4 are not interchangeable, even when they look similar in a file list. Save an MP4 of a public YouTube video you have the right to keep. Use it only for a video you own, recorded, or have permission to download. Phones, browsers, Instagram, YouTube, and WhatsApp all expect MP4.
Paste the link and download an MP4 when the stream can be fetched.
The YouTube file you already have
A YouTube link points at a public video. It is not a file on your computer until a tool fetches it. Private, live, members-only, and age-restricted videos fail. YouTube also blocks third-party access without notice.
You are not uploading your own file. The link is sent to the server so the stream can be fetched, and the download is not kept as a library.
What a MP4 result is for
The download has to be MP4, because that is the format the next step named. Phones, browsers, Instagram, YouTube, and WhatsApp all expect MP4. If the other person can open only one video format, MP4 is that format.
A new encode cannot look cleaner than the MP4 you started with. A remux on a desktop is the lossless path when the streams are already compatible.
How to tell that YouTube to MP4 worked
YouTube to MP4 is worth using only when MP4 is what the next step actually named. Save an MP4 of a public YouTube video you have the right to keep. What you get from YouTube to MP4: Paste the link and download an MP4 when the stream can be fetched. Before you trust it: Only content you own or are allowed to download. Live streams and private videos will not work. Expect occasional failures when YouTube changes access rules. The link is sent to the server so a public stream can be fetched. The download is not kept. Most other tools on this site never upload the file. A second pass rarely helps. If the first MP4 file is rejected, read the error from the program that rejected it. Another conversion of a bad result usually makes the file worse, not more compatible. When you are done, you should still have the YouTube original and one MP4 download that you have opened. If those two are the same kind of failure, this was the wrong tool and the page above is the place that says so. YouTube to MP4 is only for a public video you are allowed to save. Private, live, members-only, and age-restricted links fail, and YouTube can block a fetch that worked last month. The link is sent so the stream can be fetched. The file is not kept. Copyright still applies even when the download succeeds.
Here is the decision for YouTube to MP4. You start with YouTube and you stop when a real program accepts MP4. A public watch, Shorts, or youtu.be link can be saved as audio or video when YouTube allows the fetch. Soft subtitles such as ASS or PGS, and extra audio languages, are awkward or dropped when a tool re-encodes. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
Only content you own or are allowed to download. Live streams and private videos will not work. Expect occasional failures when YouTube changes access rules.
A related step, if you still need one, is YouTube to MP3.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.