.@TeamYouTube I am trying to upload an m4v file to YouTube via Chrome but the upload page shifts to all white moments after the file is brought in. I have tried FireFox and the same issue is occurring. m4v files are what I always upload and have no issues with.
We'd like to look into it. Could you try clearing your browser's cache and cookies? Here's how: https://yt.be/help/9RPp . Also, could you try it on different device to see if that makes any difference? Keep us posted.