I tried again and it failed at Fri Apr7 16:57:31 CDT 2017. The Session ID is 9eeacf23-9ea5-491a-b607-97ae635ebb84 and the User ID is 1e2ba46a-0544-4f17-ae79-4e3ded424cde.
For what it is worth, it looks like the XHR receieved an HTTP 403 on a PUT right before the error.
"Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://web.microsoftstream.com' is therefore not allowed access."
Based off the errors I saw in the console, I am assuming that a security token weasn't getting extended or renewed on each put of the video chunk, and ultimately it expired causing the upload to fail.
I was able to get an internet connection with a specifically fast upload speed and was able to upload the videos successfully on that connection. The problem is repeatable on my normal Internet connection, so if it is something you would like help troubleshooting, please let me know and I can re-test and give feedback.