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)
It's subtle, and it's cheeky, but it can be done:

Given a particular channel URL:

<https://www.youtube.com/channel/UC9mPk8yIk1AUC8PDsUYFBaA>

You can fiddle a little bit and:

<https://www.youtube.com/playlist?list=UU9mPk8yIk1AUC8PDsUYFBaA>

Note that you change `channel/UC` to `playlist?list=UU`.

`$ echo "$URL" | sed 's/channel\/UC/playlist\?list=UU/'`

You don't need to have a particular video.

The playlist can't be sorted, saved or manipulated in any useful way (at time of writing), but when you hit "Play all" or pick a video you can use the shuffle button in the playlist.