You mentioned Criken, he’s a partner so past broadcasts are retained for 60 days. If you look at his video list Twitch there is a dropdown box, anything that is in the highlights section will always be available, but things that are a past broadcast and not a highlight will be removed after 60 days. If the VOD you bookmarked was never made a highlight, or reuploaded, then it will expire if too much time has passed.