lcof

It is more or less this. But after two conventional disputes, the alleged copyright holder cannot just claim it again. They need to go into the DMCA legal process - as so far this was just YouTube backed policy. Once a DMCA takedown received a counter-notification (disputing it), the alleged copyright owner has to either file a lawsuit, or just back out. They won’t be able to either claim the content or take it down again (unless they use shady techniques, which could get them in trouble). In a vast majority of cases, they won’t file a lawsuit, even more in this specific case of a very short excerpt, which could fall into fair use anyway.

The claim could be audiovisual or audio only, and might be for the whole video or just a few short segments. The claim might also apply different policies based on territories (public domain in the US does not imply it is public domain worldwide). If you are sure about it, then dispute the claim, and dispute the next one if necessary, even if that’s under DMCA. Then all they can do is file a lawsuit, which they won’t do. Full disclosure: I worked with contentID for the past 10 years.