At Netflix, in my larger work group, we have at least 7 FreeBSD committers, and one core team member (and I'm sure I'm forgetting some folks and I'm sorry!). We have employed (on specific contracts) many other committers and core team members.

Unlike Yahoo, we are accountable to Netflix's business goals of increasing our streaming customer's Quality of Experience while still maintaining or reducing the cost to deliver content. Frequently those goals align nicely with FreeBSD's goals, and we have contributed a great deal (async sendfile, kTLS, unmapped mbufs, epoch stabilization, NUMA work, RACK TCP, BBR TCP, TCP pacing, and tons of stuff I'm forgetting).