The more up-to-date answer is here: https://support.google.com/youtube/answer/71673?hl=en
15 minutes is the default max length, but that can be extended by visiting https://www.youtube.com/verify The webpage says to make sure you’re using an ‘up-to-date’ version of your browser to upload files over 20GB. The current (as of Nov 12, 2016) maximum file size is 128GB and the maximum duration is 12 hours.