Generally, it is all right to use YouTube videos in your hubs without permission as the action of uploading his video onto YouTube automatically gives you permission to use it.
However, you may still be liable to copyright infringement and other issues. Some things that you want to look out for include:
- the person uploading the video does not hold the copyright.
- there is an identifiable person or persons in the video who did not give their consent.
- there are commercial products or trademarks or excerpts from copyrighted works in the video.