There are a few common practices for configuring when backups occur. The most common option is on a fixed schedule, such as once a day, week, or month. The second, which we prefer, is to upload file changes whenever they're changed and saved, otherwise known as a continuous backup setting. Services only transfer the modified part of the file in this scenario, so as not to overburden your internet connection or take up unnecessary storage. A third way is simply to upload files manually. Some may appreciate this degree of control, but this method is only effective if you remember to regularly run the backup.
The next page will show a list of all Google products associated with your account whose data can be backed up. All of them will be selected by default, so make sure to unselect all and select only youtube. An easy way would be to untick the "Select All" button at the top which will unselect all items. Then scroll down and check the "YouTube" option.