Wrong video title, description, or thumbnail on Facebook
When entering a YouTube URL to Facebook, the auto-populated video title, description, or thumbnail may occasionally be blank or out of date. This can happen when a YouTube video is shared on Facebook or entered into a post before the video has finished processing or while the video is private.
Occasionally, even after the video has finished processing and is made public, an out-of-date title, description, or thumbnail may appear. This will eventually fix itself once Facebook updates its cache.
How to update the title or description immediately
If you are the uploader and want to ensure that other users will see the correct title and description when sharing your video on Facebook, you can enter the video URL in the Facebook debug tool to immediately update the cached title and description.
If you run into other issues, consider reporting the issue to Facebook.
How to avoid this issue
When you upload a video, make sure that the video is processed, made public, and that the video information and thumbnail are set on YouTube before pasting the video link in Facebook. Pasting the link will load the video information at that moment into Facebook's cache. Even if the title or description is changed on YouTube, the old information will persist for any user who pastes that URL until Facebook’s cache is updated.