You can either:
Get your API key from Google Cloud API, choose Credentials and show an API key. (I chose Browser Key 3.)
export YTKEY=[YOURAPIKEY]
Get ChannelId from the channel's main page:
Then you can use the YouTube v3 API to retrieve playlists for that channel.
curl "https://www.googleapis.com/youtube/v3/playlists?part=snippet&channelId=UCIA9jUDnKVMYc4SmqTxcwqg&maxResults=50&key=$YTKEY"
This resulted in:
{ "kind": "youtube#playlistListResponse", "etag": "Z2DN9FRRZRRZIWx2HM8EsNieJoE", "pageInfo": { "totalResults": 38, "resultsPerPage": 50 }, "items": [ { "kind": "youtube#playlist", "etag": "2hc5G5VuRmc6R1CeDQnc9C0UNSY", "id": "PL2DcNkn8HAwR_7sj9S_shla9Wc521w6YW", "snippet": { "publishedAt": "2013-10-21T16:37:48.416149Z", "channelId": "UCIA9jUDnKVMYc4SmqTxcwqg", "title": "Latest Bravest Warriors",
Find your playlist, and get the feed. This one worked (but not always, sometimes a 404, maybe because rate limited):
https://www.youtube.com/feeds/videos.xml?playlist_id=PL2DcNkn8HAwR_7sj9S_shla9Wc521w6YW
Otherwise, if a channel has one main upload feed, you can follow these instructions to make a playlist feed directly from a channel ID.
I'm still getting 404s for these two feeds. :/
This is My public Favorites feed, so you'd hope this would work: https://www.youtube.com/feeds/videos.xml?playlist_id=FLEggwBSd9sM3nG3drXQjFhQ.
Channel ID for Extra History: UCCODtTcd5M1JavPCOr_Uydg. So presumably replace UC with UULF to convert the Channel ID to one of its playlists, this would work https://www.youtube.com/feeds/videos.xml?playlist_id=UULFCODtTcd5M1JavPCOr_Uydg
Also, API gave:
{ "kind": "youtube#playlist", "etag": "3i7uh4VFKeulC4sorjGgR63D4Ho", "id": "PLhyKYa0YJ_5BVvwMI_412K7PKndtzHTBa", "snippet": { "publishedAt": "2024-05-16T20:26:10.943743Z", "channelId": "UCCODtTcd5M1JavPCOr_Uydg", "title": "Extra History Complete", "description": "#History #Documentary #Explained #Education #WorldHistory",
So you'd hope https://www.youtube.com/feeds/videos.xml?playlist_id=PLhyKYa0YJ_5BVvwMI_412K7PKndtzHTBa would be valid.