Question: For example, I want to play all 58 videos uploaded by a single user.

Obviously I could create a playlist, add each video to it, then play the entire playlist, but is there a simpler way?

Answer: 
Much easier way now:

1. Go to the user's Youtube home page (e.g. <https://www.youtube.com/user/xyz/> ).
2. Hover over the "Uploads" section. You will see a "Play all" button appear next to "Uploads".
3. Click on "Play all" and it will generate a playlist with all the user's uploaded videos from newest to oldest. (I just wish there was an easy option to sort from oldest to newest)

Screenshot:

[![enter image description here](https://i.stack.imgur.com/ibDca.png)](https://i.stack.imgur.com/ibDca.png)
You could also use this site here: <http://youtube.nestharion.de>

It creates a playlist with all the videos from a user and plays them continually.