What are the default export settings when I choose to upload to YouTube in Final Cut Pro X? I'm trying to upload a video to YouTube from Final Cut Pro X. When I use the Share > YouTube option, the upload happens pretty well. 

There are bugs though: it asks me for my password 10+ times, it uses defaults that are different than the ones on YouTube.com, etc.

Furthermore, I also want to have a copy of the exact exported file so I can upload on other sites too.

Because of all of these, I'd prefer to export my video into the file system, and go to YouTube.com and manually upload it there (rather than having Final Cut Pro X upload it for me automatically).

However, when I go to export the video, I'm not sure what is the best format to use when uploading to YouTube:



Presumably Final Cut Pro X already figured it out and is using the best format settings when you choose to upload to YouTube. However, it doesn't show you which settings it uses:



What settings is it using to export a video when I choose the YouTube option?



I tried doing my own investigation by uploading to YouTube and then downloading the vide, but the problem is that the downloaded video from YouTube is significantly smaller (and in a different format) than the ones you upload.

For example, when I chose to export using the following Video codecs, I got these file sizes, and these download sizes:


Source (Apple ProRes 422): Exported a .mov at 4GB. When downloaded via YouTube, it was an mp4 at 18MB.
H.264: Exported a .mov at 400MB. When downloaded via YouTube, it was an mp4 at 18MB.


Interestingly enough, when uploading to YouTube on the website, it said:


  Video / Audio quality:
  Your videos will process faster if you encode into a streamable file format. For more information, visit our Help Center.


... which shows these ideal settings:


  


However, even when I try to upload an H.264 encoded .mov file, it shows me this warning. Is it because it's not in .mp4 format? And if so, how do I export as .mp4 format?
I'm not 100% sure this is the correct settings, but it does seem to be closer to the real thing since YouTube no longer shows the warning when you use these settings.

They key seems to use H.264 with the .mp4 format. The way to choose mp4, is to change the Format from Video and Audio (.mov), to Computer (.mp4):



This uploads cleanly to YouTube with no warnings, and also produces a video that is half the size of the .mov file (200MB instead of 400MB).

If you find yourself wanting to use this solution many times, you might as well create a new destination, Prepare for YouTube:



Note that the resolution settings are not 16:9 in the last screenshot (i.e. they are 4096 x 2160 instead of what is ideal on YouTube for 4K: 3840 x 2160). This means you'll need to manually choose this setting each time in the share screen.

Note: When you try to download the video on YouTube, you might expect it to download the original mp4 you uploaded (200MB), but you'll find that the video that is downloaded is much smaller (18MB). You can therefore not use YouTube as a way to backup your exported mp4. You should still store it on some other medium or service.