We made a cat drink a beer with Runway’s AI video generator, and it sprouted hands

In June, Runway debuted a new text-to-video synthesis model called Gen-3 Alpha. It converts written descriptions called “prompts” into HD video clips without sound. We’ve since had a chance to use it and wanted to share our results. Our tests show that careful prompting isn’t as important as matching concepts likely found in the training data, and that achieving amusing results likely requires many generations and selective cherry-picking.

An enduring theme of all generative AI models we’ve seen since 2022 is that they can be excellent at mixing concepts found in training data but are typically very poor at generalizing (applying learned “knowledge” to new situations the model has not explicitly been trained on). That means they can excel at stylistic and thematic novelty but struggle at fundamental structural novelty that goes beyond the training data.

What does all that mean? In the case of Runway Gen-3, lack of generalization means you might ask for a sailing ship in a swirling cup of coffee, and provided that Gen-3’s training data includes video examples of sailing ships and swirling coffee, that’s an “easy” novel combination for the model to make fairly convincingly. But if you ask for a cat drinking a can of beer (in a beer commercial), it will generally fail because there aren’t likely many videos of photorealistic cats drinking human beverages in the training data. Instead, the model will pull from what it has learned about videos of cats and videos of beer commercials and combine them. The result is a cat with human hands pounding back a brewsky.

(Update: Runway has not revealed where it got its training data, but after the publication of this article, 404 Media posted a report that seems to show that much of the video data came from an unauthorized scrape of YouTube videos.)

A few basic prompts

During the Gen-3 Alpha testing phase, we signed up for Runway’s Standard plan, which provides 625 credits for $15 a month, plus some bonus free trial credits. Each generation costs 10 credits per one second of video, and we created 10-second videos for 100 credits a piece. So the quantity of generations we could make were limited.

We first tried a few standards from our image synthesis tests in the past, like cats drinking beer, barbarians with CRT TV sets, and queens of the universe. We also dipped into Ars Technica lore with the “moonshark,” our mascot. You’ll see all those results and more below.

We had so few credits that we couldn’t afford to rerun them and cherry-pick, so what you see for each prompt is exactly the single generation we received from Runway.

“A highly-intelligent person reading “Ars Technica” on their computer when the screen explodes”

“commercial for a new flaming cheeseburger from McDonald’s”

“The moonshark jumping out of a computer screen and attacking a person”

“A cat in a car drinking a can of beer, beer commercial”

“Will Smith eating spaghetti” triggered a filter, so we tried “a black man eating spaghetti.” (Watch until the end.)

“Robotic humanoid animals with vaudeville costumes roam the streets collecting protection money in tokens”

“A basketball player in a haunted passenger train car with a basketball court, and he is playing against a team of ghosts”

“A herd of one million cats running on a hillside, aerial view”

“video game footage of a dynamic 1990s third-person 3D platform game starring an anthropomorphic shark boy”

Some notable failures

The current state of Runway’s video synthesis tech already contains plenty of conceptual errors, as you’ve seen above. So that brings up a good question: What should we consider a generation failure when we are generally pleased that a cat suddenly sprouted a human hand while drinking a can of beer?

In this case, we feel that there were times when the AI model did not follow the prompt very closely—either thematically or suggested camera movements. And at a bare minimum, these generations failed to entertain us.

“Benj Edwards, a computer journalist, writing about AI on a typewriter that turns into a robot”

“fast motion zoom in and spin around a beautiful queen of the universe”

“A scared woman in a Victorian outfit running through a forest, dolly shot”

“a muscular barbarian with weapons beside a CRT television set, cinematic, 8K, studio lighting”

“aerial shot of a small American town getting deluged with liquid cheese after a massive cheese rainstorm where liquid cheese rained down and dripped all over the buildings”

Experimenting with more detailed prompts

Since building good prompts for Gen-3 can be tricky, someone created a GPT assistant (for ChatGPT) that can help convert simple prompts into more descriptive prompting language that includes more detailed camera instructions. Using that GPT, we created the following generations: