The issue here is that a channel is not a playlist; channels can have multiple playlists, yet the listType parameter is designed to look for an actual playlist info object. The documented way around this is to use the data API and call the channel endpoint, looking at the contentDetails part:
GET https://www.googleapis.com/youtube/v3/channels?part=contentDetails&id=UCuo5NTU3pmtPejmlzjCgwdw&key={YOUR_API_KEY}
The result will give you all of the feeds associated with that channel that you can choose from:
"contentDetails": {
"relatedPlaylists": {
"uploads": "UUuo5NTU3pmtPejmlzjCgwdw"
}
}
If available (sometimes with oAuth), there could also be "watch later" lists, "likes" lists, etc.
This may seem like a lot of overhead. In the short term, though, it can be noted that the different feeds are programmatically named; so, for example, if my user channel begins with UC and then a long string, that UC stands for 'user channel' -- and the uploads feed would begin with 'UU' (user uploads) and then have the rest of the same long string. (you'd also have 'LL' for the likes list, 'WL' for the watch later list, 'HL' for the history list, 'FL' for the favorites list, etc. This is NOT documented, and so there's no guarantee that such a naming convention will perpetuate. But at least for now, you could change your ID string from beginning with UC to beginning with UU, like this:
http://www.youtube.com/embed/?listType=user_uploads&list=UUpAOGs57EWRvOPXQhnYHpow
And it embeds nicely.
