Video Conferencing Applications (VCAs) employ real-time congestion (rate) control algorithms on top of UDP. In this paper, we take an in-depth look at the congestion control behavior of four proprietary VCAs: Zoom, Microsoft Teams, Google Meet, and Cisco Webex. We compare their startup phases, bandwidth probing behaviors, and reactions to packet delays and drops. We uncover previously-unknown bandwidth estimation strategies, and tradeoffs in how quickly they react to available bandwidth changes. Our study is based on over 130 h of VCA traffic data collected under diverse network conditions and two buffer sizes, and annotated with sending rate, buffer occupancy, packet drop, and several user Quality of Experience (QoE) metrics. Our dataset is publicly available to support further research in understanding VCA performance ( https://www.cs.purdue.edu/homes/fahmy/datasets/VCAPurdue/ ).