About speaker

Serban Petrescu

Trilogy

SVP of Engineering

Builder and technical leader serving as SVP of Software Engineering at Trilogy, where Serban leads 0→1 product development across a portfolio of educational technology products.

Serban’s edtech work spans three pillars: learning applications (7+ apps including AI tutoring, spaced repetition games, and adaptive learning platforms), content generation infrastructure (curriculum modeling, AI-powered content authoring, publishing workflows), and learning analytics (student engagement tracking, mastery measurement, outcome correlation).

He has implemented learning science principles directly into products he’s built: spaced repetition algorithms, mastery-based progression, automaticity building, active learning over passive consumption, and knowledge graph-driven curricula. This work enables thousands of students at Alpha School to achieve 99th percentile test results.

Serban believes that education should be extremely personalized and ruthlessly efficient. The traditional model wastes time – students sit passively, then learn separately. The opportunity is teaching the right things in the right order, with maximum engagement and zero wasted time.

Talk details

Talk
AI/ML

Your Vision Model Is Biased: Lessons From Shipping Real-Time Video Detection

Serban Petrescu
Serban Petrescu SVP of Engineering at Trilogy

We put students in front of a webcam to protect the integrity of remote standardized tests. Then our production pipeline started flagging kids for phone use while they drank from a water bottle. On the hard cases, two times out of three.

This talk is about how to build near-real-time detection on vision LLMs. I’ll walk the pipeline end to end: segmenting live video, running VLM passes over short windows, and turning raw model output into signals you can trust.

Every lesson here was measured against a human-annotated data set. The video format you send moves accuracy more than the model you pick: one input change cut false positives by 27 points. Telling the model to “be careful” buys almost nothing, because vision-model language priors override the pixels, a failure two 2026 papers quantify. Two frontier models were unusable for us.

And evaluation, not generation, is the hard part. When two annotators watched the same video and disagreed on what counted as cheating, we handed the same footage to ten people, just to force the argument out into the open. That pushed us to write an objective grading rubric for our annotation team, then to rebuild the scoring logic around difficulty and ambiguity instead of a flat pass or fail.

You leave with a repeatable way to build and evaluate vision detection pipelines, and a sharper distrust of your own metrics.

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Data

Leadership

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AI/ML

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