YouTube to MP4 for Editing: Keep the Quality
For a remix video, a beat breakdown, a lyric video or a cover you want to line up with the original, you need the picture as well as the sound. That means an MP4. The right one drops straight into your editor at full quality. The wrong one looks soft, stutters on the timeline or gives you audio that falls apart once you start processing it.
Pick the quality your project runs at
Download at the resolution of your timeline, not lower. A 1080p project needs a 1080p file: scaling a 720p file up to fill the frame makes it visibly softer, and no export setting gets that detail back. Going above your timeline gains nothing either, so for most edits 1080p is the right choice.
Size grows with length and movement. A 10 minute video is usually 150 to 300 MB at 1080p and 80 to 130 MB at 720p. If you only need the clip as a rough reference to score against, 720p is plenty and loads faster in the editor.
What is inside a YouTube MP4
A standard YouTube MP4 holds H.264 video and AAC audio. That pair is the most widely supported format there is: Premiere Pro, DaVinci Resolve, Final Cut, CapCut and iMovie open it without converting, and Ableton Live and Reaper can load it as a video track so you can write or sync music against the picture.
YouTube also keeps the original frame rate, whether that is 24, 25, 30 or 60 frames per second. Set your project to the same rate before you drop the clip in. A 60 fps clip on a 30 fps timeline drops every other frame, and a 25 fps clip on a 30 fps timeline stutters.
Converting the video to MP4
Copy the video link from the Share button or the address bar, paste it into YT to MP4, a free YouTube to MP4 converter made by the AudioForges developer, and pick 1080p. It needs no sign-up, shows the file size before you download, and copies YouTube's stream as it is instead of compressing it again, so the picture you edit is the picture YouTube sent. Videos up to 60 minutes come in HD.
When you need better audio than the MP4
The audio inside the MP4 is AAC at around 128 kbps. That is fine for watching and for a rough cut, but it is lossy, and the losses show once you start processing: pitch shifting, time stretching, heavy EQ or pulling out stems all make the artefacts louder.
If the sound matters, take it separately. Use the YouTube to WAV converter for an uncompressed copy to edit, or the YouTube Vocal Remover if you need the vocal or the instrumental on its own. Both files start at the same moment as the video, so you can drop the WAV under the MP4, line both up at zero, and mute the MP4's own audio.
Only use what you are allowed to
Downloading a video does not give you the right to reuse it. Stick to your own uploads, videos the creator lets you use, or content under a licence that covers what you are making. For anything you plan to publish, check the licence before you start editing, not after.