Explain that if they do not remove their copyright claim within the time allotted that I will revoke their rights to use my footage in their video due to a terms of use violation.
The DMCA states they are filing the take down under penalty of perjury. It's very slippery though.
If Sony says "This is A, and I own A. Take down Small Time's video." Then all is good so long as Sony actually owns A. If the content is B, it's a great inconvenience to Small Time, but there's really no recourse.
However, what Sony did was say "This is B, I own B. Take down Small Time's video." The content IS B. Sony has misrepresented their ownership of B. Now they've perjured themselves.
My understanding is that perjury is punishable by up to five years in prison. It seems like someone at Sony should now be under investigation for this little 'oops.' Even if Small Time is satisfied with the outcome, it sounds like someone at Sony still violated the law.