HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

The issue is likely not related to that; even in the older version of HoMM3 HD 3.07f (15.10.2012), the final video after completing a map is displayed. Perhaps the problem lies in the specific version of "Heroes" being used, and that version simply has this video removed. There seem to be countless different repack versions available, ranging from completely complete ones (nothing removed) to utterly poor ones (everything possible has been removed to save a few more bytes).