Mood: The mood of the video appears to be nostalgic and classic, with a hint of mystery and intrigue. The theme seems to be related to a detective story, given the title 'Detective Byomkesh Bakshy'. The emotions conveyed are those of suspense, curiosity, and possibly romance.

Environment: The setting of the video seems to be a mix of old, possibly vintage, environments, including what appears to be a train, a traditional Indian setting, and dimly lit, atmospheric spaces. The overall setting suggests a period or retro-style detective film.