Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Re: How to add items to "Watch Later" and create playlist's from the YouTube Roku channel
Thanks for the note here.
For more information about that channel's features and functionality, you'll want to contact YouTube support directly to inquire further. Each channel on Roku is developed and maintained by the channel provider themselves.