SD processing on YouTube takes between 10 minutes to an hour depending on the size of the video.
Smaller videos will take less time for SD processing on YouTube while larger videos will take longer for SD processing.
In general, for every minute of video uploaded, it can take between 30 seconds and 1 minute to complete processing for HD videos.
This means that a 10-minute video can take between 5 minutes and 10 minutes to process completely.
You can leave YouTube while uploading a video but you must keep the YouTube browser tab open that the video is uploading from.
So you can open a new tab on the browser and watch other YouTube videos or do something else while the YouTube video is uploading.
You can turn off your computer while YouTube video is processing.
When your YouTube video is processing it means that the video is uploaded to the YouTube servers and the servers are processing your video to be available to watch.
The YouTube video will continue processing if you turn off your computer.
However if the YouTube video is still uploading and you shut off your computer then the YouTube video upload will fail because it needs your computer to be on to upload.
But once the YouTube video is uploaded to YouTube and is in the processing stage it's fine to shut off your computer or close the browser tab.