Please answer these questions when reporting a new issue:
What is your operating system (Windows, Linux, OSX, etc.)?
What is your web server (Apache, IIS, etc.)?
What version of Alltube are you using?
How did you install Alltube (with Git or with a release package)?
What version of PHP are you using?
What version of Python are you using?
What version of youtube-dl are you using?
Do you get any PHP-related errors in your webserver's logs?
What is the content of your config/config.yml file?
Please provide the URL of a video that causes the issue.