When using the YouTube Channel widget, you must be careful to use only one of three options for linking the channel.
Video URL (the full permalink found in your browser’s search bar, not the share link!)
Using the video’s shortened share link below the video is not advised, and will almost always produce a YouTube error. Please use the full video URL.
Find the YouTube Channel ID in the URL after clicking on the YouTube username video, as shown below.
Find the YouTube username on the user’s channel (in many cases, this may be the same as the channel ID).
Use the full video URL, which can be found in the address bar of your browser.