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)
Little trick I found is to get a user's unique code/string from their profile page's source. Here's how to do it:

* Go to their user page and right-click -> "view page source".
* Search for "vnd" and copy the code that you find (It should start with "UC").
* Open one of the user's videos. In the URL address, add the following to the end: "&list=" then paste the string you copied.
* Final step is simply change the 2nd character of the code you pasted from a C to a U. Hit enter and the video should reload, and now it appears in a playlist of all the user's videos.

This seems to work pretty reliably, but sometimes does not get all of the user's videos.