I contacted Warner Bros. Games and received a clear answer: the company has no objection to non-commercial fan projects, provided three rules are followed — use legal copies, do not monetize the finished video, and create content in good taste.
Pavel Golovin’s project will be strictly non-commercial:
✓ You won’t pay a single cent to watch the finished film
✓ The creators will not make any profit
✓ Donations go exclusively toward the production of the project