Microsoft·Machine Learning Engineer·Onsite - System Design / Architecture
Apr 2026
A deep system design round at Microsoft for an ML engineer role, focused entirely on building a video VLM from the ground up. The scope was massive and they expected you to connect data, modeling, training, and eval into one coherent story, then tie it back to something you'd actually shipped.
- Design a video Vision-Language Model end-to-end, covering data sourcing and preprocessing, model architecture, training strategy, and evaluation. Then walk through a past project and explain what you'd do differently with this design.
- How would you source and build a training dataset for a video VLM, including captioning pipelines, multimodal alignment data, and filtering or deduplication?
- What are the trade-offs between different video encoder architectures like ViT with frame sampling, 3D CNNs, and perceiver-based models for a video understanding task?
- Walk through the pretraining objectives you'd use for a video VLM, such as contrastive learning, captioning, or masked language modeling, and how you'd stage the training.
- How would you evaluate a video VLM across retrieval, captioning, and visual question answering benchmarks, and where does human evaluation fit in?
“This was basically four questions in a trench coat.” The rest of the author's notes on Machine Learning Engineer interview at Microsoft, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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