LLMJunky says Opus 5.5 made a 36-minute educational film

• Opus 5.5 reportedly wrote and produced a 36-minute educational film: LLMJunky put the spend at more than $200.
• The final animations were JavaScript, according to the creator's clarification; none of the attempted Veo 3.1 clips made the cut.
• Opus selected the music and image tools itself, LLMJunky explained in a reply. The human prescribed Gemini 3.8 Flash TTS for narration.
• The production included human supervision: LLMJunky periodically watched and steered during the early stages.

The narrator was meant to have a distinguished English accent from a century ago. Opus called in judges to choose the music and voice, then gave itself end credits.

LLMJunky gave Opus permission to use API keys in their keychain to generate voices, imagery, video and explanatory motion graphics. The creator described the experiment as a way to make bespoke educational films for their children.

The History of Light, posted by LLMJunky, runs 35 minutes and 37 seconds.

The published prompt combined a history syllabus with specific production constraints:

• History: Who studied light, what people believed at each stage, who dissented, and how long those beliefs persisted.
• Physics: The experiments behind those debates, with an in-depth treatment of particle-wave duality.
• Narration: Gemini 3.8 Flash TTS, with a slow, distinguished English accent “from 100 years ago.”
• Writing and code: Only Opus 5.5, using high reasoning, for both the story and programming.
• Iteration: Work until “excellence,” with as many subagents and tokens as needed.

The published brief specified neither a target runtime nor a dollar cap.

Opus tried Veo 3.1, but none of those clips survived into the final cut. It wrote the final animations in JavaScript, the standout creative choice in this production.

Veo 3.1 generates eight-second clips with native audio, according to Google's documentation. LLMJunky did not give a reason for excluding the attempted clips.

Five media models supplied assets, according to LLMJunky's production account:

• Gemini 3.8 Flash TTS: Narration.
• Lyrica 3: Background music.
• GPT Image 2.5: Scene imagery.
• Nano Banana Pro: Scene imagery.
• NB2 Flash: Scene imagery.

Only the TTS model was prescribed by the creator; Opus selected the other tools itself.

Opus tried alternatives and launched judges to pick the musical score and voice, LLMJunky said. The creator described that trial-and-error process as one of the impressive parts of the run.

Google documents regional accents and consistent voice identity across multi-minute narration for Gemini 3.8 Flash TTS. Those are vendor-described capabilities, separate from the creator's account of how Opus selected the audio.

LLMJunky described several boundaries around the delegated production:

• Supervision: The creator periodically watched and steered the early stages.
• Animation direction: They wanted something like 3Blue1Brown's animations, but only requested impressive diagrams and animations, as their follow-up explains. They never explicitly named that reference to Opus.
• Missing coverage: The creator wished the film had covered more about light and time.

LLMJunky attributed the unexpectedly high spend to giving Opus too much freedom with API keys. They said the project did not necessarily require that much money.

The run used roughly 30-40% of their weekly allowance, LLMJunky estimated in another reply. They left the flaws unfixed because the project was already expensive, describing their own contribution as guidance rather than repairs.

Anthropic's Opus 5.5 launch pricing lists standard API rates of $4 per million input tokens and $20 per million output tokens. LLMJunky's post gives an overall project spend rather than a service-by-service bill.

For a separate joke chart, LLMJunky said they asked GPT Image 2.5 for “Excalidraw art style.” The same image model appeared in the film's asset list.